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KSH(1)				 User commands				KSH(1)

NAME
       ksh - Public domain Korn shell

SYNOPSIS
       ksh [±abCefhikmnprsuvxX] [±o option] [ [ -c command-string [command-
       name] | -s | file ] [argument ...] ]

DESCRIPTION
       ksh is a command interpreter that is intended for both interactive  and
       shell  script  use.   Its  command  language is a superset of the sh(1)
       shell language.

   Shell Startup
       The following options can be specified only on the command line:

       -c command-string
	      the shell executes the command(s) contained in command-string

       -i     interactive mode — see below

       -l     login shell — see below interactive mode — see below

       -s     the shell reads commands from  standard  input;  all  non-option
	      arguments are positional parameters

       -r     restricted mode — see below

       In  addition  to	 the  above, the options described in the set built-in
       command can also be used on the command line.

       If neither the -c nor the -s options  are  specified,  the  first  non-
       option  argument	 specifies the name of a file the shell reads commands
       from; if there are no non-option arguments, the	shell  reads  commands
       from  standard input.  The name of the shell (i.e., the contents of the
       $0) parameter is determined as follows: if the -c option	 is  used  and
       there is a non-option argument, it is used as the name; if commands are
       being read from a file, the file is used as  the	 name;	otherwise  the
       name the shell was called with (i.e., argv[0]) is used.

       A  shell	 is  interactive  if the -i option is used or if both standard
       input and standard error are attached to a tty.	An  interactive	 shell
       has  job control enabled (if available), ignores the INT, QUIT and TERM
       signals, and prints prompts before  reading  input  (see	 PS1  and  PS2
       parameters).   For non-interactive shells, the trackall option is on by
       default (see set command below).

       A shell is restricted if the -r option is used or if either  the	 base‐
       name of the name the shell is invoked with or the SHELL parameter match
       the pattern *r*sh (e.g.,	 rsh,  rksh,  rpdksh,  etc.).	The  following
       restrictions come into effect after the shell processes any profile and
       $ENV files:
	 ·    the cd command is disabled
	 ·    the SHELL, ENV and PATH parameters can't be changed
	 ·    command names can't be specified with absolute or relative paths
	 ·    the -p option of the command built-in can't be used
	 ·    redirections that create files can't be used (i.e., >,  >|,  >>,
	      <>)

       A  shell	 is privileged if the -p option is used or if the real user-id
       or group-id does not match  the	effective  user-id  or	group-id  (see
       getuid(2), getgid(2)).  A privileged shell does not process $HOME/.pro‐
       file nor the ENV parameter (see below), instead the file /etc/suid_pro‐
       file  is processed.  Clearing the privileged option causes the shell to
       set its effective user-id (group-id) to its real user-id (group-id).

       If the basename of the name the shell is called	with  (i.e.,  argv[0])
       starts with - or if the -l option is used, the shell is assumed to be a
       login shell and the shell reads and executes the contents of  /etc/pro‐
       file and $HOME/.profile if they exist and are readable.

       If  the	ENV parameter is set when the shell starts (or, in the case of
       login shells, after any profiles are processed), its value is subjected
       to  parameter,  command,	 arithmetic  and  tilde	 substitution  and the
       resulting file (if any) is read and executed.  If ENV parameter is  not
       set  (and  not  null) and pdksh was compiled with the DEFAULT_ENV macro
       defined, the file named in that macro is included (after the above men‐
       tioned substitutions have been performed).

       The  exit  status  of the shell is 127 if the command file specified on
       the command line could not be opened, or non-zero  if  a	 fatal	syntax
       error  occurred	during	the  execution of a script.  In the absence of
       fatal errors, the exit status is that of the last command executed,  or
       zero, if no command is executed.

   Command Syntax
       The  shell  begins parsing its input by breaking it into words.	Words,
       which are sequences of characters, are  delimited  by  unquoted	white-
       space  characters (space, tab and newline) or meta-characters (<, >, |,
       ;, &, ( and )).	Aside from  delimiting	words,	spaces	and  tabs  are
       ignored,	 while newlines usually delimit commands.  The meta-characters
       are used in building the following tokens: <, <&, <<, >, >&,  >>,  etc.
       are  used to specify redirections (see Input/Output Redirection below);
       | is used to create pipelines; |& is used to create  co-processes  (see
       Co-Processes  below); ; is used to separate commands; & is used to cre‐
       ate asynchronous pipelines; && and || are used to  specify  conditional
       execution;  ;;  is used in case statements; (( .. )) are used in arith‐
       metic expressions; and lastly, ( .. ) are used to create subshells.

       White-space and meta-characters can be quoted individually using	 back‐
       slash  (\),  or	in groups using double (") or single (') quotes.  Note
       that the following characters are also treated specially by  the	 shell
       and  must be quoted if they are to represent themselves: \, ", ', #, $,
       `, ~, {, }, *, ? and [.	The first three of these are  the  above  men‐
       tioned quoting characters (see Quoting below); #, if used at the begin‐
       ning of a word, introduces a comment — everything after the # up to the
       nearest	newline	 is ignored; $ is used to introduce parameter, command
       and arithmetic substitutions (see Substitution below); ` introduces  an
       old-style  command  substitution	 (see  Substitution below); ~ begins a
       directory expansion (see Tilde Expansion below); { and } delimit csh(1)
       style  alternations (see Brace Expansion below); and, finally, *, ? and
       [ are used in file name generation (see File Name Patterns below).

       As words and tokens are parsed, the shell  builds  commands,  of	 which
       there are two basic types: simple-commands, typically programs that are
       executed, and compound-commands, such as for and if statements,	group‐
       ing constructs and function definitions.

       A  simple-command consists of some combination of parameter assignments
       (see Parameters below),	input/output  redirections  (see  Input/Output
       Redirections  below),  and  command words; the only restriction is that
       parameter assignments come  before  any	command	 words.	  The  command
       words,  if any, define the command that is to be executed and its argu‐
       ments.  The command may be a shell built-in command, a function	or  an
       external	 command,  i.e.,  a  separate  executable file that is located
       using the PATH parameter (see Command Execution below).	Note that  all
       command	constructs have an exit status: for external commands, this is
       related to the status returned by wait(2) (if the command could not  be
       found,  the  exit  status is 127, if it could not be executed, the exit
       status is 126); the exit status of other command	 constructs  (built-in
       commands, functions, compound-commands, pipelines, lists, etc.) are all
       well defined and are described where the construct is  described.   The
       exit  status  of	 a command consisting only of parameter assignments is
       that of the last command substitution performed	during	the  parameter
       assignment or zero if there were no command substitutions.

       Commands	 can  be chained together using the | token to form pipelines,
       in which the standard output of each command but the last is piped (see
       pipe(2)) to the standard input of the following command.	 The exit sta‐
       tus of a pipeline is that of its last command.  A pipeline may be  pre‐
       fixed  by the ! reserved word which causes the exit status of the pipe‐
       line to be logically complemented: if the original  status  was	0  the
       complemented  status  will  be 1, and if the original status was not 0,
       then the complemented status will be 0.

       Lists of commands can be created by separating pipelines by any of  the
       following  tokens:  &&,	||, &, |& and ;.  The first two are for condi‐
       tional execution: cmd1 && cmd2 executes cmd2 only if the exit status of
       cmd1  is	 zero;	|| is the opposite — cmd2 is executed only if the exit
       status of cmd1 is non-zero.  && and || have equal precedence  which  is
       higher than that of &, |& and ;, which also have equal precedence.  The
       & token causes the preceding command  to	 be  executed  asynchronously,
       that is, the shell starts the command, but does not wait for it to com‐
       plete (the shell does keep track of the status of asynchronous commands
       — see Job Control below).  When an asynchronous command is started when
       job control is disabled (i.e., in most scripts), the command is started
       with  signals  INT  and	QUIT  ignored  and  with input redirected from
       /dev/null (however, redirections specified in the asynchronous  command
       have precedence).  The |& operator starts a co-process which is special
       kind of asynchronous process (see Co-Processes  below).	 Note  that  a
       command	must  follow the && and || operators, while a command need not
       follow &, |& and ;.  The exit status of a list is that of the last com‐
       mand  executed, with the exception of asynchronous lists, for which the
       exit status is 0.

       Compound commands are created using  the	 following  reserved  words  —
       these  words  are  only recognized if they are unquoted and if they are
       used as the first word of a command (i.e., they can't  be  preceded  by
       parameter assignments or redirections):

			 case	else   function	  then	  !
			 do	esac   if	  time	  [[
			 done	fi     in	  until	  {
			 elif	for    select	  while	  }
       Note: Some shells (but not this one) execute control structure commands
       in a subshell when one or more of  their	 file  descriptors  are	 redi‐
       rected,	so any environment changes inside them may fail.  To be porta‐
       ble, the exec  statement	 should	 be  used  instead  to	redirect  file
       descriptors before the control structure.

       In  the following compound command descriptions, command lists (denoted
       as list) that are followed by reserved words  must  end	with  a	 semi-
       colon, a newline or a (syntactically correct) reserved word.  For exam‐
       ple,
	      { echo foo; echo bar; }
	      { echo foo; echo bar<newline>}
	      { { echo foo; echo bar; } }
       are all valid, but
	      { echo foo; echo bar }
       is not.

       ( list )
	      Execute list in a subshell.  There is no implicit	 way  to  pass
	      environment changes from a subshell back to its parent.

       { list }
	      Compound	construct;  list  is  executed, but not in a subshell.
	      Note that { and } are reserved words, not meta-characters.

       case word in [ [(] pattern [| pattern] ... ) list ;; ] ... esac
	      The case statement attempts to match word against the  specified
	      patterns;	 the  list  associated	with  the  first  successfully
	      matched pattern is executed.  Patterns used in  case  statements
	      are  the	same  as those used for file name patterns except that
	      the restrictions regarding . and / are dropped.  Note  that  any
	      unquoted space before and after a pattern is stripped; any space
	      with a pattern must be quoted.  Both the word and	 the  patterns
	      are  subject  to parameter, command, and arithmetic substitution
	      as well as tilde substitution.  For historical reasons, open and
	      close braces may be used instead of in and esac (e.g., case $foo
	      { *) echo bar; }).  The exit status of a case statement is  that
	      of the executed list; if no list is executed, the exit status is
	      zero.

       for name [ in word ... term ] do list done
	      where term is either a newline or a ;.  For  each	 word  in  the
	      specified	 word  list, the parameter name is set to the word and
	      list is executed.	 If in is not used to specify a word list, the
	      positional  parameters ("$1", "$2", etc.) are used instead.  For
	      historical reasons, open and close braces may be used instead of
	      do  and  done (e.g., for i; { echo $i; }).  The exit status of a
	      for statement is the last exit status of list; if list is	 never
	      executed, the exit status is zero.

       if list then list [elif list then list] ... [else list] fi
	      If the exit status of the first list is zero, the second list is
	      executed; otherwise the list following the elif, if any, is exe‐
	      cuted with similar consequences.	If all the lists following the
	      if and elifs fail (i.e., exit with non-zero  status),  the  list
	      following the else is executed.  The exit status of an if state‐
	      ment is that of non-conditional list that	 is  executed;	if  no
	      non-conditional list is executed, the exit status is zero.

       select name [ in word ... term ] do list done
	      where  term  is  either  a newline or a ;.  The select statement
	      provides an automatic method of presenting the user with a  menu
	      and  selecting  from  it.	  An  enumerated list of the specified
	      words is printed on standard error, followed by a	 prompt	 (PS3,
	      normally	`#?  ').  A number corresponding to one of the enumer‐
	      ated words is then read from standard input, name is set to  the
	      selected word (or is unset if the selection is not valid), REPLY
	      is set to what was read (leading/trailing	 space	is  stripped),
	      and  list	 is executed.  If a blank line (i.e., zero or more IFS
	      characters) is entered, the menu is re-printed without executing
	      list.   When  list  completes, the enumerated list is printed if
	      REPLY is null, the prompt is printed and so on.  This process is
	      continues until an end-of-file is read, an interrupt is received
	      or a break statement is executed inside the loop.	  If  in  word
	      ...  is omitted, the positional parameters are used (i.e., "$1",
	      "$2", etc.).  For historical reasons, open and close braces  may
	      be  used	instead of do and done (e.g., select i; { echo $i; }).
	      The exit status of a select statement is zero if a break	state‐
	      ment is used to exit the loop, non-zero otherwise.

       until list do list done
	      This  works  like	 while,	 except that the body is executed only
	      while the exit status of the first list is non-zero.

       while list do list done
	      A while is a prechecked loop.  Its body is executed as often  as
	      the exit status of the first list is zero.  The exit status of a
	      while statement is the last exit status of the list in the  body
	      of  the  loop;  if  the body is not executed, the exit status is
	      zero.

       function name { list }
	      Defines the function name.   See	Functions  below.   Note  that
	      redirections specified after a function definition are performed
	      whenever the function is executed, not when the function defini‐
	      tion is executed.

       name () command
	      Mostly the same as function.  See Functions below.

       time [ -p ] [ pipeline ]
	      The  time	 reserved  word	 is described in the Command Execution
	      section.

       (( expression ))
	      The arithmetic expression expression is evaluated; equivalent to
	      let  "expression".   See Arithmetic Expressions and the let com‐
	      mand below.

       [[ expression ]]
	      Similar to the test and [ ... ] commands (described later), with
	      the following exceptions:
		·    Field  splitting  and  file  name generation are not per‐
		     formed on arguments.
		·    The -a (and) and -o (or) operators are replaced  with  &&
		     and ||, respectively.
		·    Operators (e.g., -f, =, !, etc.) must be unquoted.
		·    The  second  operand of != and = expressions are patterns
		     (e.g., the comparison in
					[[ foobar = f*r ]]
		     succeeds).
		·    There are two additional binary operators: < and >	 which
		     return  true  if their first string operand is less than,
		     or greater than, their  second  string  operand,  respec‐
		     tively.
		·    The  single  argument  form  of  test, which tests if the
		     argument has non-zero length, is  not  valid  -  explicit
		     operators must be always be used, e.g., instead of
					      [ str ]
		     use
					   [[ -n str ]]
		·    Parameter,	 command and arithmetic substitutions are per‐
		     formed as expressions are evaluated and  lazy  expression
		     evaluation	 is  used  for	the && and || operators.  This
		     means that in the statement
				  [[ -r foo && $(< foo) = b*r ]]
		     the $(< foo) is evaluated if and only  if	the  file  foo
		     exists and is readable.

   Quoting
       Quoting	is used to prevent the shell from treating characters or words
       specially.  There are three methods of quoting:	First,	\  quotes  the
       following  character,  unless it is at the end of a line, in which case
       both the \ and the newline are stripped.	 Second, a  single  quote  (')
       quotes  everything  up  to the next single quote (this may span lines).
       Third, a double quote (") quotes all characters, except $, ` and \,  up
       to  the	next unquoted double quote.  $ and ` inside double quotes have
       their usual meaning (i.e., parameter, command or	 arithmetic  substitu‐
       tion)  except  no field splitting is carried out on the results of dou‐
       ble-quoted substitutions.  If a \ inside a double-quoted string is fol‐
       lowed by \, $, ` or ", it is replaced by the second character; if it is
       followed by a newline, both the \ and the newline are stripped;	other‐
       wise, both the \ and the character following are unchanged.

       Note:  see  POSIX  Mode below for a special rule regarding sequences of
       the form "...`...\"...`..".

   Aliases
       There are two types of aliases:	normal	command	 aliases  and  tracked
       aliases.	  Command aliases are normally used as a short hand for a long
       or often used command.  The shell expands command aliases  (i.e.,  sub‐
       stitutes	 the alias name for its value) when it reads the first word of
       a command.  An  expanded	 alias	is  re-processed  to  check  for  more
       aliases.	 If a command alias ends in a space or tab, the following word
       is also checked for alias expansion.  The alias expansion process stops
       when  a word that is not an alias is found, when a quoted word is found
       or when an alias word that is currently being expanded is found.

       The following command aliases are defined automatically by the shell:
	      autoload='typeset -fu'
	      functions='typeset -f'
	      hash='alias -t'
	      history='fc -l'
	      integer='typeset -i'
	      local='typeset'
	      login='exec login'
	      newgrp='exec newgrp'
	      nohup='nohup '
	      r='fc -e -'
	      stop='kill -STOP'
	      suspend='kill -STOP $$'
	      type='whence -v'

       Tracked aliases allow the shell to remember where it found a particular
       command.	  The  first  time  the shell does a path search for a command
       that is marked as a tracked alias, it saves the full path of  the  com‐
       mand.   The  next  time	the  command is executed, the shell checks the
       saved path to see that it is still valid, and if so,  avoids  repeating
       the path search.	 Tracked aliases can be listed and created using alias
       -t.  Note that changing the PATH parameter clears the saved  paths  for
       all  tracked  aliases.	If  the	 trackall  option is set (i.e., set -o
       trackall or set -h), the shell tracks all commands.  This option is set
       automatically for non-interactive shells.  For interactive shells, only
       the following commands are automatically tracked: cat, cc,  chmod,  cp,
       date, ed, emacs, grep, ls, mail, make, mv, pr, rm, sed, sh, vi and who.

   Substitution
       The first step the shell takes in executing a simple-command is to per‐
       form substitutions on the words of the command.	There are three	 kinds
       of  substitution: parameter, command and arithmetic.  Parameter substi‐
       tutions, which are described in detail in the next  section,  take  the
       form $name or ${...}; command substitutions take the form $(command) or
       `command`; and arithmetic substitutions take the form $((expression)).

       If a substitution appears outside of double quotes, the results of  the
       substitution are generally subject to word or field splitting according
       to the current value of the IFS parameter.  The IFS parameter specifies
       a  list	of characters which are used to break a string up into several
       words; any characters from the set space, tab and newline  that	appear
       in  the IFS characters are called IFS white space.  Sequences of one or
       more IFS white space characters, in combination with zero or  one  non-
       IFS white space characters delimit a field.  As a special case, leading
       and trailing IFS white space is stripped (i.e., no leading or  trailing
       empty  field is created by it); leading or trailing non-IFS white space
       does create an empty field.  Example: if IFS is set to `<space>:',  the
       sequence	 of  characters	 `<space>A<space>:<space><space>B::D' contains
       four fields: `A', `B', `' and `D'.  Note that if the IFS	 parameter  is
       set to the null string, no field splitting is done; if the parameter is
       unset, the default value of space, tab and newline is used.

       The results of substitution are, unless otherwise specified, also  sub‐
       ject  to brace expansion and file name expansion (see the relevant sec‐
       tions below).

       A command substitution is replaced by the output generated by the spec‐
       ified  command,	which  is run in a subshell.  For $(command) substitu‐
       tions, normal quoting rules are used when command is  parsed,  however,
       for the `command` form, a \ followed by any of $, ` or \ is stripped (a
       \ followed by any other character is unchanged).	 As a special case  in
       command	substitutions,	a command of the form < file is interpreted to
       mean substitute the contents of file ($(< foo) has the same  effect  as
       $(cat  foo),  but it is carried out more efficiently because no process
       is started).
       NOTE: $(command) expressions are currently parsed by finding the match‐
       ing  parenthesis,  regardless of quoting.  This will hopefully be fixed
       soon.

       Arithmetic substitutions are replaced by the  value  of	the  specified
       expression.   For  example, the command echo $((2+3*4)) prints 14.  See
       Arithmetic Expressions for a description of an expression.

   Parameters
       Parameters are shell variables; they can be assigned values  and	 their
       values  can  be	accessed  using a parameter substitution.  A parameter
       name is either one of the special single punctuation or digit character
       parameters  described  below, or a letter followed by zero or more let‐
       ters or digits (`_' counts as a letter).	 The later form can be treated
       as arrays by appending an array index of the form: [expr] where expr is
       an arithmetic expression.  Array indicies are currently limited to  the
       range 0 through 1023, inclusive.	 Parameter substitutions take the form
       $name, ${name} or ${name[expr]}, where name is a	 parameter  name.   If
       substitution  is	 performed  on a parameter (or an array parameter ele‐
       ment) that is not set, a null string is substituted unless the  nounset
       option  (set  -o	 nounset  or  set  -u)	is set, in which case an error
       occurs.

       Parameters can be assigned values in a  number  of  ways.   First,  the
       shell  implicitly  sets	some parameters like #, PWD, etc.; this is the
       only way the special single  character  parameters  are	set.   Second,
       parameters  are	imported  from	the  shell's  environment  at startup.
       Third, parameters can be assigned values on the command line, for exam‐
       ple,  `FOO=bar'	sets  the  parameter  FOO  to  bar; multiple parameter
       assignments can be given on a single command line and they can be  fol‐
       lowed  by a simple-command, in which case the assignments are in effect
       only for the  duration  of  the	command	 (such	assignments  are  also
       exported,  see  below  for  implications	 of this).  Note that both the
       parameter name and the = must be unquoted for the shell to recognize  a
       parameter  assignment.	The  fourth way of setting a parameter is with
       the export, readonly and typeset commands; see  their  descriptions  in
       the Command Execution section.  Fifth, for and select loops set parame‐
       ters as well as the getopts, read and set -A commands.  Lastly, parame‐
       ters  can  be  assigned values using assignment operators inside arith‐
       metic expressions (see  Arithmetic  Expressions	below)	or  using  the
       ${name=value} form of parameter substitution (see below).

       Parameters  with	 the export attribute (set using the export or typeset
       -x commands, or by parameter assignments followed by  simple  commands)
       are  put	 in  the  environment  (see environ(5)) of commands run by the
       shell as name=value pairs.  The order in which parameters appear in the
       environment  of a command is unspecified.  When the shell starts up, it
       extracts parameters and their values from its environment and automati‐
       cally sets the export attribute for those parameters.

       Modifiers can be applied to the ${name} form of parameter substitution:

       ${name:-word}
	      if  name	is set and not null, it is substituted, otherwise word
	      is substituted.

       ${name:+word}
	      if name is set and not  null,  word  is  substituted,  otherwise
	      nothing is substituted.

       ${name:=word}
	      if  name is set and not null, it is substituted, otherwise it is
	      assigned word and the resulting value of name is substituted.

       ${name:?word}
	      if name is set and not null, it is substituted,  otherwise  word
	      is  printed  on  standard error (preceded by name:) and an error
	      occurs (normally causing termination of a shell script, function
	      or  .-script).  If word is omitted the string `parameter null or
	      not set' is used instead.

       In the above modifiers, the : can be omitted, in which case the	condi‐
       tions  only  depend on name being set (as opposed to set and not null).
       If word is needed, parameter, command, arithmetic and  tilde  substitu‐
       tion are performed on it; if word is not needed, it is not evaluated.

       The following forms of parameter substitution can also be used:

       ${#name}
	      The  number  of  positional parameters if name is *, @ or is not
	      specified, or the length of the string value of parameter name.

       ${#name[*]}, ${#name[@]}
	      The number of elements in the array name.

       ${name#pattern}, ${name##pattern}
	      If pattern matches the beginning of the value of parameter name,
	      the  matched text is deleted from the result of substitution.  A
	      single # results in the shortest match, two #'s results  in  the
	      longest match.

       ${name%pattern}, ${name%%pattern}
	      Like  ${..#..}  substitution, but it deletes from the end of the
	      value.

       The following special parameters are implicitly set by  the  shell  and
       cannot be set directly using assignments:

       !      Process  id of the last background process started.  If no back‐
	      ground processes have been started, the parameter is not set.

       #      The number of positional parameters (i.e., $1, $2, etc.).

       $      The process ID of the shell, or the PID of the original shell if
	      it is a subshell.

       -      The  concatenation of the current single letter options (see set
	      command below for list of options).

       ?      The exit status of the last non-asynchronous  command  executed.
	      If  the  last  command  was killed by a signal, $? is set to 128
	      plus the signal number.

       0      The name the shell was invoked with (i.e., argv[0]), or the com‐
	      mand-name	 if it was invoked with the -c option and the command-
	      name was supplied, or the file argument, if it was supplied.  If
	      the posix option is not set, $0 is the name of the current func‐
	      tion or script.

       1 ... 9
	      The first nine positional parameters that were supplied  to  the
	      shell,  function or .-script.  Further positional parameters may
	      be accessed using ${number}.

       *      All positional parameters (except	 parameter  0),	 i.e.,	$1  $2
	      $3....   If  used outside of double quotes, parameters are sepa‐
	      rate words (which are subjected  to  word	 splitting);  if  used
	      within  double  quotes,  parameters  are	separated by the first
	      character of the IFS parameter (or the empty string  if  IFS  is
	      null).

       @      Same  as	$*,  unless  it is used inside double quotes, in which
	      case a separate word is generated for each positional  parameter
	      -	 if  there  are no positional parameters, no word is generated
	      ("$@" can be used to access arguments, verbatim, without loosing
	      null arguments or splitting arguments with spaces).

       The following parameters are set and/or used by the shell:

       _ (underscore)
	      When  an external command is executed by the shell, this parame‐
	      ter is set in the environment of the new process to the path  of
	      the  executed  command.	In  interactive use, this parameter is
	      also set in the parent shell to the last word  of	 the  previous
	      command.	 When  MAILPATH messages are evaluated, this parameter
	      contains the name of the file that changed (see MAILPATH parame‐
	      ter below).

       CDPATH Search  path for the cd built-in command.	 Works the same way as
	      PATH for those directories not beginning with / in cd  commands.
	      Note  that  if CDPATH is set and does not contain . nor an empty
	      path, the current directory is not searched.

       COLUMNS
	      Set to the number of columns on the terminal  or	window.	  Cur‐
	      rently  set  to  the  cols  value as reported by stty(1) if that
	      value is non-zero.  This parameter is used  by  the  interactive
	      line  editing  modes, and by select, set -o and kill -l commands
	      to format information in columns.

       EDITOR If the VISUAL parameter is not set, this parameter controls  the
	      command  line  editing  mode for interactive shells.  See VISUAL
	      parameter below for how this works.

       ENV    If this parameter is found to be set after any profile files are
	      executed,	 the  expanded value is used as a shell start-up file.
	      It typically contains function and alias definitions.

       ERRNO  Integer value of the shell's errno variable — indicates the rea‐
	      son the last system call failed.

	      Not implemented yet.

       EXECSHELL
	      If  set,	this parameter is assumed to contain the shell that is
	      to be used to execute commands that execve(2) fails  to  execute
	      and which do not start with a `#! shell' sequence.

       FCEDIT The editor used by the fc command (see below).

       FPATH  Like  PATH,  but	used when an undefined function is executed to
	      locate the file defining the function.  It is also searched when
	      a	 command  can't	 be found using PATH.  See Functions below for
	      more information.

       HISTFILE
	      The name of the file used to store history.  When	 assigned  to,
	      history  is loaded from the specified file.  Also, several invo‐
	      cations of the shell running on the same machine will share his‐
	      tory if their HISTFILE parameters all point at the same file.
	      NOTE:  if	 HISTFILE isn't set, no history file is used.  This is
	      different	  from	 the   original	  Korn	 shell,	  which	  uses
	      $HOME/.sh_history;  in future, pdksh may also use a default his‐
	      tory file.

       HISTSIZE
	      The number of commands normally stored for history, default 128.

       HOME   The default directory for the cd command and the	value  substi‐
	      tuted for an unqualified ~ (see Tilde Expansion below).

       IFS    Internal	field  separator,  used during substitution and by the
	      read command, to split values into distinct arguments;  normally
	      set  to  space,  tab  and	 newline.   See Substitution above for
	      details.
	      Note: this parameter is not imported from the  environment  when
	      the shell is started.

       KSH_VERSION
	      The version of shell and the date the version was created (read‐
	      only).  See also the version commands in Emacs Editing Mode  and
	      Vi Editing Mode sections, below.

       LINENO The  line	 number	 of  the function or shell script that is cur‐
	      rently being executed.

       LINES  Set to the number of lines on the terminal or window.

	      Not implemented yet.

       MAIL   If set, the user will be informed of the arrival of mail in  the
	      named file.  This parameter is ignored if the MAILPATH parameter
	      is set.

       MAILCHECK
	      How often, in seconds, the shell will  check  for	 mail  in  the
	      file(s)  specified  by MAIL or MAILPATH.	If 0, the shell checks
	      before each prompt.  The default is 600 (10 minutes).

       MAILPATH
	      A list of files to be checked for mail.  The list is colon sepa‐
	      rated,  and each file may be followed by a ? and a message to be
	      printed if new mail has arrived.	Command, parameter and	arith‐
	      metic substitution is performed on the message, and, during sub‐
	      stitution, the parameter $_ contains the name of the file.   The
	      default message is you have mail in $_.

       OLDPWD The  previous  working  directory.  Unset if cd has not success‐
	      fully changed directories since the shell	 started,  or  if  the
	      shell doesn't know where it is.

       OPTARG When  using  getopts,  it	 contains  the	argument  for a parsed
	      option, if it requires one.

       OPTIND The index of the last argument  processed	 when  using  getopts.
	      Assigning	 1  to	this parameter causes getopts to process argu‐
	      ments from the beginning the next time it is invoked.

       PATH   A colon separated list of directories  that  are	searched  when
	      looking  for  commands and .'d files.  An empty string resulting
	      from a leading or trailing colon,	 or  two  adjacent  colons  is
	      treated as a `.', the current directory.

       POSIXLY_CORRECT
	      If  set,	this  parameter causes the posix option to be enabled.
	      See POSIX Mode below.

       PPID   The process ID of the shell's parent (readonly).

       PS1    PS1 is the primary prompt for  interactive  shells.   Parameter,
	      command  and  arithmetic	substitutions  are performed, and ! is
	      replaced with the current command number (see fc command below).
	      A literal ! can be put in the prompt by placing !! in PS1.  Note
	      that since the command line editors try to figure out  how  long
	      the  prompt  is  (so  they  know	how  far  it is to edge of the
	      screen), escape codes in the prompt tend to mess things up.  You
	      can  tell	 the  shell  not  to  count certain sequences (such as
	      escape codes) by prefixing your prompt with a non-printing char‐
	      acter (such as control-A) followed by a carriage return and then
	      delimiting the escape codes with	this  non-printing  character.
	      If  you  don't  have  any non-printing characters, you're out of
	      luck...  BTW, don't blame me for this hack; it's in the original
	      ksh.  Default is `$ ' for non-root users, `# ' for root..

       PS2    Secondary	 prompt	 string, by default `> ', used when more input
	      is needed to complete a command.

       PS3    Prompt used by select statement when reading a  menu  selection.
	      Default is `#? '.

       PS4    Used  to prefix commands that are printed during execution trac‐
	      ing (see set -x command below).  Parameter, command  and	arith‐
	      metic substitutions are performed before it is printed.  Default
	      is `+ '.

       PWD    The current working directory.  Maybe unset  or  null  if	 shell
	      doesn't know where it is.

       RANDOM A	 simple	 random number generator.  Every time RANDOM is refer‐
	      enced, it is assigned the next number in a random number series.
	      The point in the series can be set by assigning a number to RAN‐
	      DOM (see rand(3)).

       REPLY  Default parameter for the read command if no  names  are	given.
	      Also  used  in select loops to store the value that is read from
	      standard input.

       SECONDS
	      The number of seconds since the shell started or, if the parame‐
	      ter  has	been  assigned an integer value, the number of seconds
	      since the assignment plus the value that was assigned.

       TMOUT  If set to a positive integer in an interactive shell, it	speci‐
	      fies the maximum number of seconds the shell will wait for input
	      after printing  the  primary  prompt  (PS1).   If	 the  time  is
	      exceeded, the shell exits.

       TMPDIR The  directory  shell  temporary	files are created in.  If this
	      parameter is not set, or does not contain the absolute path of a
	      writable directory, temporary files are created in /tmp.

       VISUAL If  set,	this  parameter controls the command line editing mode
	      for interactive shells.  If the last component of the path spec‐
	      ified  in this parameter contains the string vi, emacs or gmacs,
	      the vi, emacs or gmacs (Gosling emacs) editing mode is  enabled,
	      respectively.

   Tilde Expansion
       Tilde expansion, which is done in parallel with parameter substitution,
       is done on words starting with an unquoted ~.  The characters following
       the  tilde,  up to the first /, if any, are assumed to be a login name.
       If the login name is empty, + or -, the value of the HOME, PWD, or OLD‐
       PWD  parameter  is  substituted, respectively.  Otherwise, the password
       file is searched for the login name, and the tilde expression  is  sub‐
       stituted	 with  the  user's  home  directory.  If the login name is not
       found in the password file or if any quoting or parameter  substitution
       occurs in the login name, no substitution is performed.

       In  parameter  assignments  (those  preceding a simple-command or those
       occurring in the arguments of alias, export,  readonly,	and  typeset),
       tilde  expansion	 is done after any unquoted colon (:), and login names
       are also delimited by colons.

       The home directory of previously expanded login names  are  cached  and
       re-used.	  The  alias -d command may be used to list, change and add to
       this cache (e.g., `alias -d fac=/usr/local/facilities; cd ~fac/bin').

   Brace Expansion (alternation)
       Brace expressions, which take the form
	      prefix{str1,...,strN}suffix
       are expanded to N words, each of which is the concatenation of  prefix,
       stri  and  suffix  (e.g.,  `a{c,b{X,Y},d}e'  expands to four word: ace,
       abXe, abYe, and ade).  As noted in the example, brace  expressions  can
       be  nested  and	the resulting words are not sorted.  Brace expressions
       must contain an unquoted comma (,) for expansion to occur (i.e., {} and
       {foo}  are not expanded).  Brace expansion is carried out after parame‐
       ter substitution and before file name generation.

   File Name Patterns
       A file name pattern is a word containing one or more unquoted  ?	 or  *
       characters or [..] sequences.  Once brace expansion has been performed,
       the shell replaces file name patterns with the sorted names of all  the
       files  that  match  the	pattern	 (if  no files match, the word is left
       unchanged).  The pattern elements have the following meaning:

       ?      matches any single character.

       *      matches any sequence of characters.

       [..]   matches any of the characters inside the	brackets.   Ranges  of
	      characters can be specified by separating two characters by a -,
	      e.g., [a0-9] matches the letter a or any	digit.	 In  order  to
	      represent itself, a - must either be quoted or the first or last
	      character in the character list.	Similarly, a ] must be	quoted
	      or  the  first  character	 in the list if it is represent itself
	      instead of the end of the list.  Also, a	!   appearing  at  the
	      start  of the list has special meaning (see below), so to repre‐
	      sent itself it must be quoted or appear later in the list.

       [!..]  like [..], except it matches any character not inside the brack‐
	      ets.

       *(pattern| ... |pattern)
	      matches any string of characters that matches zero or more occu‐
	      rances  of  the  specified  patterns.   Example:	 the   pattern
	      *(foo|bar)  matches  the	strings `', `foo', `bar', `foobarfoo',
	      etc..

       +(pattern| ... |pattern)
	      matches any string of characters that matches one or more	 occu‐
	      rances   of   the	 specified  patterns.	Example:  the  pattern
	      +(foo|bar) matches the strings `foo', `bar', `foobarfoo', etc..

       ?(pattern| ... |pattern)
	      matches the empty string or a string that	 matches  one  of  the
	      specified	  patterns.   Example:	the  pattern  ?(foo|bar)  only
	      matches the strings `', `foo' and `bar'.

       @(pattern| ... |pattern)
	      matches a string that matches one	 of  the  specified  patterns.
	      Example:	the  pattern @(foo|bar) only matches the strings `foo'
	      and `bar'.

       !(pattern| ... |pattern)
	      matches any string that does not match one of the specified pat‐
	      terns.   Examples:  the  pattern	!(foo|bar) matches all strings
	      except `foo' and `bar'; the pattern !(*) matches no strings; the
	      pattern !(?)* matches all strings (think about it).

       Note that pdksh currently never matches . and .., but the original ksh,
       Bourne sh and bash do, so this may have to change (too bad).

       Note that none of the above pattern elements match either a period  (.)
       at the start of a file name or a slash (/), even if they are explicitly
       used in a [..] sequence; also, the names . and ..  are  never  matched,
       even by the pattern .*.

       If  the	markdirs  option is set, any directories that result from file
       name generation are marked with a trailing /.

       The POSIX character classes (i.e., [:class-name:] inside a [..] expres‐
       sion) are not yet implemented.

   Input/Output Redirection
       When  a	command	 is  executed, its standard input, standard output and
       standard error (file descriptors 0, 1 and 2, respectively) are normally
       inherited  from	the  shell.   Three exceptions to this are commands in
       pipelines, for which standard input and/or standard  output  are	 those
       set  up by the pipeline, asynchronous commands created when job control
       is disabled, for which standard input  is  initially  set  to  be  from
       /dev/null,  and	commands  for  which any of the following redirections
       have been specified:

       > file standard output is redirected to file.  If file does not	exist,
	      it  is  created;	if  it	does  exist, is a regular file and the
	      noclobber option is set, an error occurs, otherwise the file  is
	      truncated.   Note	 that  this  means the command cmd < foo > foo
	      will open foo for reading and then truncate it when it opens  it
	      for writing, before cmd gets a chance to actually read foo.

       >| file
	      same  as	>, except the file is truncated, even if the noclobber
	      option is set.

       >> file
	      same as >, except the file  an  existing	file  is  appended  to
	      instead  of being truncated.  Also, the file is opened in append
	      mode, so writes always go to the end of the file (see open(2)).

       < file standard input is redirected from	 file,	which  is  opened  for
	      reading.

       <> file
	      same as <, except the file is opened for reading and writing.

       << marker
	      after reading the command line containing this kind of redirect‐
	      ion (called a here document), the shell copies  lines  from  the
	      command  source  into  a	temporary  file	 until a line matching
	      marker is read.  When the command is executed, standard input is
	      redirected  from	the  temporary	file.	If  marker contains no
	      quoted characters, the contents of the temporary file  are  pro‐
	      cessed  as if enclosed in double quotes each time the command is
	      executed, so parameter, command and arithmetic substitutions are
	      performed,  along	 with  backslash  (\)  escapes for $, `, \ and
	      \newline.	 If multiple here documents are used on the same  com‐
	      mand line, they are saved in order.

       <<- marker
	      same  as	<<, except leading tabs are stripped from lines in the
	      here document.

       <& fd  standard input is duplicated from file descriptor fd.  fd can be
	      a	 single	 digit,	 indicating  the  number  of  an existing file
	      descriptor, the letter p, indicating the file descriptor associ‐
	      ated with the output of the current co-process, or the character
	      -, indicating standard input is to be closed.

       >& fd  same as <&, except the operation is done on standard output.

       In any of the above redirections, the file  descriptor  that  is	 redi‐
       rected  (i.e.,  standard	 input	or  standard output) can be explicitly
       given by preceding the redirection with	a  single  digit.   Parameter,
       command	and  arithmetic substitutions, tilde substitutions and (if the
       shell is interactive) file name generation are  all  performed  on  the
       file,  marker and fd arguments of redirections.	Note however, that the
       results of any file name generation are only used if a single  file  is
       matched;	 if  multiple  files  match, the word with the unexpanded file
       name generation characters is used.  Note that  in  restricted  shells,
       redirections which can create files cannot be used.

       For  simple-commands,  redirections may appear anywhere in the command,
       for compound-commands (if  statements,  etc.),  any  redirections  must
       appear at the end.  Redirections are processed after pipelines are cre‐
       ated and in the order they are given, so
	      cat /foo/bar 2>&1 > /dev/null | cat -n
       will print an error with a line number prepended to it.

   Arithmetic Expressions
       Integer arithmetic expressions can be used with the let command, inside
       $((..))	expressions,  inside  array  references (e.g., name[expr]), as
       numeric arguments to the test command, and as the value of  an  assign‐
       ment to an integer parameter.

       Expression  may contain alpha-numeric parameter identifiers, array ref‐
       erences, and integer constants and may be combined with the following C
       operators (listed and grouped in increasing order of precedence).

       Unary operators:
	      + - ! ~ ++ --

       Binary operators:
	      ,
	      = *= /= %= += -= <<= >>= &= ^= |=
	      ||
	      &&
	      |
	      ^
	      &
	      == !=
	      < <= >= >
	      << >>
	      + -
	      * / %

       Ternary operator:
	      ?: (precedence is immediately higher than assignment)

       Grouping operators:
	      ( )

       Integer constants may be specified with arbitrary bases using the nota‐
       tion base#number, where base is a decimal integer specifying the	 base,
       and number is a number in the specified base.

       The operators are evaluated as follows:

	      unary +
		     result is the argument (included for completeness).

	      unary -
		     negation.

	      !	     logical  not;  the	 result is 1 if argument is zero, 0 if
		     not.

	      ~	     arithmetic (bit-wise) not.

	      ++     increment; must be applied to a parameter (not a  literal
		     or other expression) - the parameter is incremented by 1.
		     When used as a prefix operator, the result is the	incre‐
		     mented  value  of	the  parameter, when used as a postfix
		     operator, the result is the original value of the parame‐
		     ter.

	      ++     similar to ++, except the paramter is decremented by 1.

	      ,	     separates	two arithmetic expressions; the left hand side
		     is evaluated first, then the right.  The result is	 value
		     of the expression on the right hand side.

	      =	     assignment;  variable  on the left is set to the value on
		     the right.

	      *= /= %= += -= <<= >>= &= ^= |=
		     assignment operators; <var> <op>= <expr> is the  same  as
		     <var> = <var> <op> ( <expr> ).

	      ||     logical  or;  the	result is 1 if either argument is non-
		     zero, 0 if not.  The right argument is evaluated only  if
		     the left argument is zero.

	      &&     logical  and;  the result is 1 if both arguments are non-
		     zero, 0 if not.  The right argument is evaluated only  if
		     the left argument is non-zero.

	      |	     arithmetic (bit-wise) or.

	      ^	     arithmetic (bit-wise) exclusive-or.

	      &	     arithmetic (bit-wise) and.

	      ==     equal;  the result is 1 if both arguments are equal, 0 if
		     not.

	      !=     not equal; the result is 0 if both arguments are equal, 1
		     if not.

	      <	     less  than;  the result is 1 if the left argument is less
		     than the right, 0 if not.

	      <= >= >
		     less than or equal, greater than or equal, greater	 than.
		     See <.

	      << >>  shift  left (right); the result is the left argument with
		     its bits shifted left (right) by the amount given in  the
		     right argument.

	      + - * /
		     addition, subtraction, multiplication, and division.

	      %	     remainder; the result is the remainder of the division of
		     the left argument by the right.  The sign of  the	result
		     is unspecified if either argument is negative.

	      <arg1> ? <arg2> : <arg3>
		     if	 <arg1>	 is  non-zero, the result is <arg2>, otherwise
		     <arg3>.

   Co-Processes
       A co-process, which is a pipeline created with the |& operator,	is  an
       asynchronous  process that the shell can both write to (using print -p)
       and read from (using read -p).  The input and output of the  co-process
       can  also  be manipulated using >&p and <&p redirections, respectively.
       Once a co-process has been started, another can't be started until  the
       co-process  exits,  or  until  the co-process input has been redirected
       using an exec n>&p redirection.	If a co-process's input is  redirected
       in  this	 way,  the next co-process to be started will share the output
       with the first co-process, unless the output of the initial  co-process
       has been redirected using an exec n<&p redirection.

       Some notes concerning co-processes:
	 ·    the  only	 way  to close the co-process input (so the co-process
	      reads an end-of-file) is to redirect the	input  to  a  numbered
	      file  descriptor and then close that file descriptor (e.g., exec
	      3>&p;exec 3>&-).
	 ·    in order for co-processes to share a common  output,  the	 shell
	      must keep the write portion of the output pipe open.  This means
	      that end of file will not be  detected  until  all  co-processes
	      sharing  the  co-process output have exited (when they all exit,
	      the shell closes its copy of the pipe).  This can be avoided  by
	      redirecting  the	output	to a numbered file descriptor (as this
	      also causes the shell to close its copy).	 Note that this behav‐
	      iour  is	slightly  different from the original Korn shell which
	      closes its copy of the write portion of the  co-processs	output
	      when  the	 most recently started co-process (instead of when all
	      sharing co-processes) exits.
	 ·    print -p will ignore SIGPIPE signals during writes if the signal
	      is not being trapped or ignored; the same is not true if the co-
	      process input has been duplicated to another file descriptor and
	      print -un is used.

   Functions
       Functions  are  defined using either Korn shell function name syntax or
       the Bourne/POSIX shell name() syntax  (see  below  for  the  difference
       between	the two forms).	 Functions are like .-scripts in that they are
       executed in the current environment, however, unlike  .-scripts,	 shell
       arguments  (i.e.,  positional  parameters,  $1, etc.) are never visible
       inside them.  When the shell is determining the location of a  command,
       functions are searched after special built-in commands, and before reg‐
       ular and non-regular built-ins, and before the PATH is searched.

       An existing function may be deleted using unset	-f  function-name.   A
       list  of	 functions  can	 be obtained using typeset +f and the function
       definitions can be listed using typeset	-f.   autoload	(which	is  an
       alias  for typeset -fu) may be used to create undefined functions; when
       an undefined function is executed, the shell searches the  path	speci‐
       fied  in the FPATH parameter for a file with the same name as the func‐
       tion, which, if found is read and executed.   If	 after	executing  the
       file,  the  named function is found to be defined, the function is exe‐
       cuted, otherwise, the normal command search  is	continued  (i.e.,  the
       shell searches the regular built-in command table and PATH).  Note that
       if a command is not found using PATH, an attempt is made to autoload  a
       function	 using	FPATH (this is an undocumented feature of the original
       Korn shell).

       Functions can have two attributes, trace and export, which can  be  set
       with typeset -ft and typeset -fx, respectively.	When a traced function
       is executed, the shell's xtrace option is turned on for	the  functions
       duration,  otherwise  the  xtrace  option  is  turned  off.  The export
       attribute of functions is currently not used.   In  the	original  Korn
       shell,  exported	 functions  are visible to shell scripts that are exe‐
       cuted.

       Since functions are executed in the current shell environment,  parame‐
       ter  assignments	 made  inside functions are visible after the function
       completes.  If this is not the desired effect, the typeset command  can
       be  used inside a function to create a local parameter.	Note that spe‐
       cial parameters (e.g., $$, $!) can't be scoped in this way.

       The exit status of a function is that of the last command  executed  in
       the  function.	A function can be made to finish immediately using the
       return command; this may also be used to explicitly  specify  the  exit
       status.

       Functions  defined  with the function reserved word are treated differ‐
       ently in the following ways from functions defined with	the  ()	 nota‐
       tion:
	 ·    the  $0  parameter  is  set to the name of the function (Bourne-
	      style functions leave $0 untouched).
	 ·    parameter assignments preceeding function calls are not kept  in
	      the  shell  environment  (executing  Bourne-style functions will
	      keep assignments).
	 ·    OPTIND is saved/reset and restored on entry and  exit  from  the
	      function so getopts can be used properly both inside and outside
	      the function (Bourne-style functions leave OPTIND untouched,  so
	      using  getopts  inside  a function interferes with using getopts
	      outside the function).  In the future, the following differences
	      will also be added:
	 ·    A	 separate trap/signal environment will be used during the exe‐
	      cution of functions.  This will mean that	 traps	set  inside  a
	      function	will not affect the shell's traps and signals that are
	      not ignored in the shell (but may be trapped)  will  have	 their
	      default effect in a function.
	 ·    The  EXIT trap, if set in a function, will be executed after the
	      function returns.

   POSIX Mode
       The shell is intended to be POSIX compliant, however,  in  some	cases,
       POSIX behaviour is contrary either to the original Korn shell behaviour
       or to user convenience.	How the shell behaves in these cases is deter‐
       mined  by  the  state of the posix option (set -o posix) — if it is on,
       the POSIX behaviour is followed, otherwise it is not.  The posix option
       is  set	automatically when the shell starts up if the environment con‐
       tains the POSIXLY_CORRECT parameter.  (The shell can also  be  compiled
       so  that	 it  is	 in POSIX mode by default, however this is usually not
       desirable).

       The following is a list of things that are affected by the state of the
       posix option:
	 ·    \"  inside  double  quoted  `..` command substitutions: in posix
	      mode, the \" is interpreted when the command is interpreted;  in
	      non-posix	 mode,	the  backslash	is stripped before the command
	      substitution is interpreted.  For example, echo "`echo  \"hi\"`"
	      produces `"hi"' in posix mode, `hi' in non-posix mode.  To avoid
	      problems, use the $(...)	form of command substitution.
	 ·    kill -l output: in posix mode, signal names  are	listed	one  a
	      single  line;  in	 non-posix  mode,  signal  numbers,  names and
	      descriptions are printed in columns.  In future,	a  new	option
	      (-v perhaps) will be added to distinguish the two behaviours.
	 ·    fg exit status: in posix mode, the exit status is 0 if no errors
	      occur; in non-posix mode, the exit status is that	 of  the  last
	      foregrounded job.
	 ·    eval  exit  status:  if eval gets to see an empty command (e.g.,
	      eval "`false`"), its exit status in posix mode will  be  0.   In
	      non-posix	 mode,	it will be the exit status of the last command
	      substitution that was done in the processing of the arguments to
	      eval (or 0 if there were no command substitutions).
	 ·    getopts:	in  posix  mode,  options must start with a -; in non-
	      posix mode, options can start with either - or +.
	 ·    brace expansion (also known  as  alternation):  in  posix	 mode,
	      brace  expansion is disabled; in non-posix mode, brace expansion
	      enabled.	Note that set -o posix (or setting the POSIXLY_CORRECT
	      parameter)  automatically turns the braceexpand option off, how‐
	      ever it can be explicitly turned on later.
	 ·    set -: in posix mode, this does not clear the verbose or	xtrace
	      options; in non-posix mode, it does.
	 ·    set  exit	 status: in posix mode, the exit status of set is 0 if
	      there are no errors; in non-posix mode, the exit status is  that
	      of  any  command	substitutions  performed in generating the set
	      command.	For example, `set -- `false`; echo  $?'	 prints	 0  in
	      posix mode, 1 in non-posix mode.	This construct is used in most
	      shell scripts that use the old getopt(1) command.
	 ·    argument expansion of alias, export, readonly, and typeset  com‐
	      mands:  in  posix	 mode, normal argument expansion done; in non-
	      posix mode, field splitting, file globing, brace	expansion  and
	      (normal)	tilde  expansion  are turned off, and assignment tilde
	      expansion is turned on.
	 ·    signal specification: in posix mode, signals can be specified as
	      digits  only  if signal numbers match POSIX values (i.e., HUP=1,
	      INT=2, QUIT=3, ABRT=6, KILL=9, ALRM=14, and  TERM=15);  in  non-
	      posix mode, signals can be always digits.
	 ·    alias  expansion: in posix mode, alias expansion is only carried
	      out when reading command words; in non-posix mode, alias	expan‐
	      sion is carried out on any word following an alias that ended in
	      a space.	For example, the following for loop
	      alias a='for ' i='j'
	      a i in 1 2; do echo i=$i j=$j; done
       uses parameter i in posix mode, j in non-posix mode.
	 ·    test: in posix mode, the expression "-t" (preceded by some  num‐
	      ber  of "!" arguments) is always true as it is a non-zero length
	      string; in non-posix mode, it tests if file descriptor  1	 is  a
	      tty  (i.e.,  the	fd argument to the -t test may be left out and
	      defaults to 1).

   Command Execution
       After evaluation of command line arguments, redirections and  parameter
       assignments,  the  type of command is determined: a special built-in, a
       function, a regular built-in or the name of a  file  to	execute	 found
       using  the  PATH	 parameter.   The  checks are made in the above order.
       Special built-in commands differ from other commands in that  the  PATH
       parameter is not used to find them, an error during their execution can
       cause a non-interactive shell to exit and  parameter  assignments  that
       are  specified before the command are kept after the command completes.
       Just to confuse things, if the posix option is turned off (see set com‐
       mand  below)  some  special  commands are very special in that no field
       splitting, file globing, brace expansion nor tilde  expansion  is  pre‐
       formed  on arguments that look like assignments.	 Regular built-in com‐
       mands are different only in that the PATH parameter is not used to find
       them.

       The  original  ksh and POSIX differ somewhat in which commands are con‐
       sidered special or regular:

       POSIX special commands

	      .		 continue   exit       return	  trap
	      :		 eval	    export     set	  unset
	      break	 exec	    readonly   shift

       Additional ksh special commands

	      builtin	 times	    typeset

       Very special commands (non-posix mode)

	      alias	 readonly   set	       typeset

       POSIX regular commands

	      alias	 command    fg	       kill	  umask
	      bg	 false	    getopts    read	  unalias
	      cd	 fc	    jobs       true	  wait

       Additional ksh regular commands

	      [		 let	    pwd	       ulimit
	      echo	 print	    test       whence

       In the future, the additional ksh special and regular commands  may  be
       treated differently from the POSIX special and regular commands.

       Once  the  type	of  the	 command has been determined, any command line
       parameter assignments are performed and exported for  the  duration  of
       the command.

       The following describes the special and regular built-in commands:

       . file [arg1 ...]
	      Execute  the  commands  in file in the current environment.  The
	      file is searched for in the directories of PATH.	 If  arguments
	      are  given, the positional parameters may be used to access them
	      while file is being executed.  If no arguments  are  given,  the
	      positional  parameters  are those of the environment the command
	      is used in.

       : [ ... ]
	      The null command.	 Exit status is set to zero.

       alias [ -d | ±t [-r] ] [±px] [±] [name1[=value1] ...]
	      Without arguments, alias lists all aliases.  For any name	 with‐
	      out  a  value,  the  existing  alias is listed.  Any name with a
	      value defines an alias (see Aliases above).

	      When listing aliases, one of  two	 formats  is  used:  normally,
	      aliases  are  listed  as	name=value,  where value is quoted; if
	      options were preceded with + or a lone + is given on the command
	      line,  only  name	 is printed.  In addition, if the -p option is
	      used, each alias is prefixed with the string "alias ".

	      The -x option sets (+x clears) the export attribute of an alias,
	      or,  if  no  names  are given, lists the aliases with the export
	      attribute (exporting an alias has no affect).

	      The  -t  option  indicates  that	tracked	 aliases  are  to   be
	      listed/set (values specified on the command line are ignored for
	      tracked aliases).	 The -r	 option	 indicates  that  all  tracked
	      aliases are to be reset.

	      The  -d causes directory aliases, which are used in tilde expan‐
	      sion, to be listed or set (see Tilde Expansion above).

       bg [job ...]
	      Resume the specified stopped job(s) in the  background.	If  no
	      jobs  are specified, %+ is assumed.  This command is only avail‐
	      able on systems which support  job  control.   See  Job  Control
	      below for more information.

       bind [-m] [key[=editing-command] ...]
	      Set  or  view  the  current  emacs  command  editing  key	 bind‐
	      ings/macros.  See	 Emacs	Editing	 Mode  below  for  a  complete
	      description.

       break [level]
	      break  exits the levelth inner most for, select, until, or while
	      loop.  level defaults to 1.

       builtin command [arg1 ...]
	      Execute the built-in command command.

       cd [-LP] [dir]
	      Set the working directory to dir.	 If the	 parameter  CDPATH  is
	      set,  it lists directories to search in for dir.	dir.  An empty
	      entry in the CDPATH entry means the  current  directory.	 If  a
	      non-empty directory from CDPATH is used, the resulting full path
	      is printed to standard output.  If  dir  is  missing,  the  home
	      directory	 $HOME	is  used.   If	dir is -, the previous working
	      directory is used (see OLDPWD parameter).	 If -L option (logical
	      path)  is used or if the physical option (see set command below)
	      isn't set, references to .. in dir are relative to the path used
	      get  to  the directory.  If -P option (physical path) is used or
	      if the physical option is set, .. is relative to the  filesystem
	      directory	 tree.	 The  PWD and OLDPWD parameters are updated to
	      reflect the current and old wording directory, respectively.

       cd [-LP] old new
	      The string new is substituted for old in the current  directory,
	      and the shell attempts to change to the new directory.

       command [-pvV] cmd [arg1 ...]
	      If  neither  the	-v  nor	 -V options are given, cmd is executed
	      exactly as if the command	 had  not  been	 specified,  with  two
	      exceptions:  first,  cmd cannot be a shell function, and second,
	      special built-in commands lose their  specialness	 (i.e.,	 redi‐
	      rection  and  utility errors do not cause the shell to exit, and
	      command assignments are not permanent).  If  the	-p  option  is
	      given,  a	 default  search  path	is used instead of the current
	      value of PATH (the actual value of the default  path  is	system
	      dependent: on POSIXish systems, it is the value returned by
				      getconf CS_PATH
	      ).

	      If the -v option is given, instead of executing cmd, information
	      about what would be executed is given (and the same is done  for
	      arg1  ...):  for special and regular built-in commands and func‐
	      tions, their names are simply printed, for  aliases,  a  command
	      that  defines them is printed, and for commands found by search‐
	      ing the PATH parameter, the full path of the command is printed.
	      If  no command is be found, (i.e., the path search fails), noth‐
	      ing is printed and command exits with a non-zero status.	The -V
	      option is like the -v option, except it is more verbose.

       continue [levels]
	      continue	jumps  to the beginning of the levelth inner most for,
	      select, until, or while loop.  level defaults to 1.

       echo [-neE] [arg ...]
	      Prints its arguments (separated by spaces) followed  by  a  new‐
	      line,  to standard out.  The newline is suppressed if any of the
	      arguments contain the backslash sequence \c.  See print  command
	      below  for  a  list of other backslash sequences that are recog‐
	      nized.

	      The options  are	provided  for  compatibility  with  BSD	 shell
	      scripts:	-n  suppresses	the trailing newline, -e enables back‐
	      slash interpretation (a no-op, since this is normally done), and
	      -E which suppresses backslash interpretation.

       eval command ...
	      The  arguments  are  concatenated	 (with spaces between them) to
	      form a single string which the shell then parses and executes in
	      the current environment.

       exec [command [arg ...]]
	      The  command  is	executed  without forking, replacing the shell
	      process.

	      If no arguments are given, any IO redirection is	permanent  and
	      the  shell is not replaced.  Any file descriptors greater than 2
	      which are opened or dup(2)-ed in this way are not made available
	      to other executed commands (i.e., commands that are not built-in
	      to the shell).  Note that the Bourne shell differs here: it does
	      pass these file descriptors on.

       exit [status]
	      The  shell  exits	 with the specified exit status.  If status is
	      not specified, the exit status is the current  value  of	the  ?
	      parameter.

       export [-p] [parameter[=value]] ...
	      Sets  the	 export	 attribute  of the named parameters.  Exported
	      parameters are passed in the environment to  executed  commands.
	      If values are specified, the named parameters also assigned.

	      If no parameters are specified, the names of all parameters with
	      the export attribute are printed one per	line,  unless  the  -p
	      option  is  used,	 in  which  case  export commands defining all
	      exported parameters, including their values, are printed.

       false  A command that exits with a non-zero status.

       fc [-e editor | -l [-n]] [-r] [first [last]]
	      first and last select commands from the history.	 Commands  can
	      be  selected  by history number, or a string specifying the most
	      recent command starting with that string.	 The -l	 option	 lists
	      the  command on stdout, and -n inhibits the default command num‐
	      bers.  The -r option reverses the order of  the  list.   Without
	      -l,  the	selected  commands  are edited by the editor specified
	      with the -e option, or if no -e is specified, the editor	speci‐
	      fied  by	the  FCEDIT  parameter	(if this parameter is not set,
	      /bin/ed is used), and then executed by the shell.

       fc [-e - | -s] [-g] [old=new] [prefix]
	      Re-execute  the  selected	 command  (the	previous  command   by
	      default)	after performing the optional substitution of old with
	      new.  If -g is specified, all occurrences of  old	 are  replaced
	      with  new.  This command is usually accessed with the predefined
	      alias r='fc -e -'.

       fg [job ...]
	      Resume the specified job(s) in the foreground.  If no  jobs  are
	      specified,  %+  is  assumed.   This command is only available on
	      systems which support job control.  See Job  Control  below  for
	      more information.

       getopts optstring name [arg ...]
	      getopts is used by shell procedures to parse the specified argu‐
	      ments (or positional parameters, if no arguments are given)  and
	      to  check for legal options.  optstring contains the option let‐
	      ters that getopts is to recognize.  If a letter is followed by a
	      colon, the option is expected to have an argument.  Options that
	      do not take arguments may be grouped in a single	argument.   If
	      an  option takes an argument and the option character is not the
	      last character of the argument it is found in, the remainder  of
	      the  argument  is	 taken to be the option's argument, otherwise,
	      the next argument is the option's argument.

	      Each time getopts is invoked, it places the next option  in  the
	      shell  parameter	name  and the index of the next argument to be
	      processed in the shell parameter	OPTIND.	  If  the  option  was
	      introduced  with a +, the option placed in name is prefixed with
	      a +.  When an option requires an argument, getopts places it  in
	      the shell parameter OPTARG.  When an illegal option or a missing
	      option argument is encountered a question mark  or  a  colon  is
	      placed  in  name	(indicating an illegal option or missing argu‐
	      ment, respectively) and OPTARG is set to	the  option  character
	      that  caused  the	 problem.  An error message is also printed to
	      standard error if optstring does not begin with a colon.

	      When the end of the options is encountered, getopts exits with a
	      non-zero	exit  status.	Options	 end  at the first (non-option
	      argument) argument that does not start with a -, or  when	 a  --
	      argument is encountered.

	      Option parsing can be reset by setting OPTIND to 1 (this is done
	      automatically  whenever  the  shell  or  a  shell	 procedure  is
	      invoked).

	      Warning:	Changing  the value of the shell parameter OPTIND to a
	      value other than 1, or parsing different sets of arguments with‐
	      out resetting OPTIND may lead to unexpected results.

       hash [-r] [name ...]
	      Without  arguments,  any hashed executable command pathnames are
	      listed.  The -r option causes all hashed commands to be  removed
	      from  the	 hash  table.	Each name is searched as if it where a
	      command name and added to the hash table if it is an  executable
	      command.

       jobs [-lpn] [job ...]
	      Display  information  about  the	specified jobs; if no jobs are
	      specified, all jobs are displayed.  The -n option causes	infor‐
	      mation  to  be  displayed	 only for jobs that have changed state
	      since the last notification.  If the  -l	option	is  used,  the
	      process-id  of  each  process  in	 a job is also listed.	The -p
	      option causes only the process group of each job to be  printed.
	      See  Job	Control	 below for the format of job and the displayed
	      job.

       kill [-s signame | -signum | -signame ] { job | pid | -pgrp } ...
	      Send the specified signal to the specified jobs, process ids, or
	      process  groups.	 If no signal is specified, the signal TERM is
	      sent.  If a job is specified, the signal is sent	to  the	 job's
	      process group.  See Job Control below for the format of job.

       kill -l [exit-status ...]
	      Print  the name of the signal that killed a process which exited
	      with the specified exit-statuses.	 If no	arguments  are	speci‐
	      fied,  a	list  of  all  the  signals, their numbers and a short
	      description of them are printed.

       let [expression ...]
	      Each expression is evaluated, see Arithmetic Expressions	above.
	      If  all  expressions are successfully evaluated, the exit status
	      is 0 (1) if the last expression evaluated	 to  non-zero  (zero).
	      If  an  error  occurs  during  the  parsing  or evaluation of an
	      expression, the exit status is greater than  1.	Since  expres‐
	      sions  may  need to be quoted, (( expr )) is syntactic sugar for
	      let "expr".

       print [-nprsun | -R [-en]] [argument ...]
	      Print prints its arguments on the standard output, separated  by
	      spaces, and terminated with a newline.  The -n option suppresses
	      the newline.  By default,	 certain  C  escapes  are  translated.
	      These  include  \b, \f, \n, \r, \t, \v, and \0### (# is an octal
	      digit, of which there may be 0 to 3).  \c is equivalent to using
	      the -n option.  \ expansion may be inhibited with the -r option.
	      The -s option prints to the history  file	 instead  of  standard
	      output, the -u option prints to file descriptor n (n defaults to
	      1 if omitted), and the -p option prints to the  co-process  (see
	      Co-Processes above).

	      The  -R  option is used to emulate, to some degree, the BSD echo
	      command, which does not process \ sequences unless the -e option
	      is  given.  As above, the -n option suppresses the trailing new‐
	      line.

       pwd [-LP]
	      Print the present working directory.  If -L option is used or if
	      the physical option (see set command below) isn't set, the logi‐
	      cal path is printed (i.e., the path used to cd  to  the  current
	      directory).   If	-P  option  (physical  path) is used or if the
	      physical option is set, the path determined from the  filesystem
	      (by following ..	directories to the root directory) is printed.

       read [-prsun] [parameter ...]
	      Reads  a	line  of  input from standard input, separate the line
	      into fields using the IFS parameter  (see	 Substitution  above),
	      and assign each field to the specified parameters.  If there are
	      more parameters than fields, the extra  parameters  are  set  to
	      null,  or	 alternatively,	 if there are more fields than parame‐
	      ters, the	 last  parameter  is  assigned	the  remaining	fields
	      (inclusive  of  any  separating  spaces).	  If no parameters are
	      specified, the REPLY parameter is used.  If the input line  ends
	      in a backslash and the -r option was not used, the backslash and
	      newline are stripped and more input is read.   If	 no  input  is
	      read, read exits with a non-zero status.

	      The  first  parameter  may  have	a  question  mark and a string
	      appended to it, in which case the string is  used	 as  a	prompt
	      (printed	to  standard  error  before  any input is read) if the
	      input is a tty (e.g., read nfoo?'number of foos: ').

	      The -un and -p options cause input to be read from file descrip‐
	      tor n or the current co-process (see Co-Processes above for com‐
	      ments on this), respectively.  If the -s option is  used,	 input
	      is saved to the history file.

       readonly [-p] [parameter[=value]] ...
	      Sets  the readonly attribute of the named parameters.  If values
	      are given,  parameters  are  set	to  them  before  setting  the
	      attribute.   Once	 a  parameter  is  made readonly, it cannot be
	      unset and its value cannot be changed.

	      If no parameters are specified, the names of all parameters with
	      the  readonly  attribute are printed one per line, unless the -p
	      option is used, in which case  readonly  commands	 defining  all
	      readonly parameters, including their values, are printed.

       return [status]
	      Returns  from  a	function or . script, with exit status status.
	      If no status is given, the exit status of the last executed com‐
	      mand is used.  If used outside of a function or . script, it has
	      the same effect as exit.	Note that pdksh	 treats	 both  profile
	      and  $ENV files as . scripts, while the original Korn shell only
	      treats profiles as . scripts.

       set [±abCefhkmnpsuvxX] [±o [option]] [±A name] [--] [arg ...]
	      The set command can be used  to  set  (-)	 or  clear  (+)	 shell
	      options,	set the positional parameters, or set an array parame‐
	      ter.  Options can be changed using the ±o option	syntax,	 where
	      option  is the long name of an option, or using the ±letter syn‐
	      tax, where letter is the option's single letter  name  (not  all
	      options  have  a single letter name).  The following table lists
	      both option letters (if they exist) and long names along with  a
	      description of what the option does.

	       -A				Sets the elements of the array
						parameter name to arg ...;  If
						-A is used, the array is reset
						(i.e., emptied) first;	if  +A
						is  used, the first N elements
						are set (where N is the number
						of  args),  the	 rest are left
						untouched.
	       -a	  allexport		all new parameters are created
						with the export attribute
	       -b	  notify		Print  job  notification  mes‐
						sages asynchronously,  instead
						of  just  before  the  prompt.
						Only used if  job  control  is
						enabled (-m).
	       -C	  noclobber		Prevent	  >  redirection  from
						overwriting existing files (>|
						must be used to force an over‐
						write).
	       -e	  errexit		Exit (after executing the  ERR
						trap)  as  soon	 as  an	 error
						occurs	or  a  command	 fails
						(i.e.,	exits  with a non-zero
						status).  This does not	 apply
						to  commands whose exit status
						is  explicitly	tested	by   a
						shell  construct  such	as if,
						until, while, && or ||	state‐
						ments.
	       -f	  noglob		Do  not	 expand file name pat‐
						terns.
	       -h	  trackall		Create tracked aliases for all
						executed commands (see Aliases
						above).	  On  by  default  for
						non-interactive shells.
	       -i	  interactive		Enable interactive mode - this
						can only be set/unset when the
						shell is invoked.
	       -k	  keyword		Parameter assignments are rec‐
						ognized anywhere in a command.
	       -l	  login			The shell is a login  shell  -
						this  can  only	 be  set/unset
						when the shell is invoked (see
						Shell Startup above).
	       -m	  monitor		Enable	job  control  (default
						for interactive shells).
	       -n	  noexec		Do not execute any commands  -
						useful for checking the syntax
						of scripts (ignored if	inter‐
						active).

	       -p	  privileged		Set automatically if, when the
						shell starts, the read uid  or
						gid  does not match the effec‐
						tive uid or gid, respectively.
						See  Shell Startup above for a
						description   of   what	  this
						means.
	       -r	  restricted		Enable	restricted mode — this
						option can only be  used  when
						the  shell  is	invoked.   See
						Shell  Startup	above  for   a
						description   of   what	  this
						means.
	       -s	  stdin			If  used  when	the  shell  is
						invoked,   commands  are  read
						from  standard	 input.	   Set
						automatically  if the shell is
						invoked with no arguments.

						When -s is  used  in  the  set
						command,  it causes the speci‐
						fied arguments	to  be	sorted
						before	assigning  them to the
						positional parameters  (or  to
						array name, if -A is used).
	       -u	  nounset		Referencing of an unset param‐
						eter is treated as  an	error,
						unless	one  of	 the -, + or =
						modifiers is used.
	       -v	  verbose		Write shell input to  standard
						error as it is read.
	       -x	  xtrace		Print  commands	 and parameter
						assignments when they are exe‐
						cuted,	preceded  by the value
						of PS4.
	       -X	  markdirs		Mark directories with a trail‐
						ing / during file name genera‐
						tion.
			  bgnice		Background jobs are  run  with
						lower priority.
			  braceexpand		Enable	brace  expansion (aka,
						alternation).
			  emacs			Enable BRL emacs-like  command
						line	editing	  (interactive
						shells only); see Emacs	 Edit‐
						ing Mode.
			  gmacs			Enable	 gmacs-like   (Gosling
						emacs)	command	 line  editing
						(interactive   shells	only);
						currently identical  to	 emacs
						editing	 except that transpose
						(^T)  acts  slightly   differ‐
						ently.
			  ignoreeof		The  shell  will  not (easily)
						exit on	 when  end-of-file  is
						read,  exit  must be used.  To
						avoid  infinite	  loops,   the
						shell will exit if eof is read
						13 times in a row.
			  nohup			Do not kill running jobs  with
						a  HUP	signal	when  a	 login
						shell exists.	Currently  set
						by   default,  but  this  will
						change in  the	future	to  be
						compatible  with  the original
						Korn shell (which doesn't have
						this option, but does send the
						HUP signal).

			  nolog			No effect -  in	 the  original
						Korn   shell,	this  prevents
						function   definitions	  from
						being  stored  in  the history
						file.
			  physical		Causes the cd and pwd commands
						to  use	 `physical' (i.e., the
						filesystem's)  ..  directories
						instead	 of `logical' directo‐
						ries (i.e.,  the shell handles
						..,  which  allows the user to
						be obliveous of symlink	 links
						to   directories).   Clear  by
						default.   Note	 that  setting
						this  option  does  not effect
						the current value of  the  PWD
						parameter; only the cd command
						changes PWD.  See the  cd  and
						pwd  commands  above  for more
						details.
			  posix			Enable posix mode.  See	 POSIX
						Mode above.
			  vi			Enable	vi-like	 command  line
						editing	 (interactive	shells
						only).
			  viraw			No  effect  -  in the original
						Korn shell, unless  viraw  was
						set,  the vi command line mode
						would let the  tty  driver  do
						the  work  until  ESC (^[) was
						entered.  pdksh is  always  in
						viraw mode.
			  vi-esccomplete	In vi command line editing, do
						command / file name completion
						when escape (^[) is entered in
						command mode.
			  vi-show8		Prefix	characters  with   the
						eighth	bit set with `M-'.  If
						this option is not set,	 char‐
						acters	in  the	 range 128-160
						are printed as is,  which  may
						cause problems.
			  vi-tabcomplete	In vi command line editing, do
						command / file name completion
						when  tab  (^I)	 is entered in
						insert mode.

	      These options can also be used upon  invocation  of  the	shell.
	      The  current  set	 of  options (with single letter names) can be
	      found in the parameter -.	 set -o with no option name will  list
	      all the options and whether each is on or off; set +o will print
	      the long names of all options that are currently on.

	      Remaining arguments, if any, are positional parameters  and  are
	      assigned,	 in  order,  to the positional parameters (i.e., 1, 2,
	      etc.).  If options are ended with -- and there are no  remaining
	      arguments, all positional parameters are cleared.	 If no options
	      or arguments are	given,	then  the  values  of  all  names  are
	      printed.	 For  unknown  historical  reasons, a lone - option is
	      treated specially: it clears both the -x and -v options.

       shift [number]
	      The positional parameters number+1, number+2 etc. are renamed to
	      1, 2, etc.  number defaults to 1.

       test expression

       [ expression ]
	      test  evaluates  the expression and returns zero status if true,
	      and 1 status if false and greater than 1 if there was an	error.
	      It  is  normally	used  as the condition command of if and while
	      statements.  The following basic expressions are available:

	       str		    str	 has  non-zero	 length.
				    Note   that	  there	 is  the
				    potential  for  problems  if
				    str turns out to be an oper‐
				    ator (e.g., -r) - it is gen‐
				    erally  better to use a test
				    like
						  [ X"str" !=  X
						  ]
					   instead	 (double
					   quotes  are	used  in
					   case	  str	contains
					   spaces or file  glob‐
					   ing characters).
	       -r file		    file exists and is readable.
	       -w file		    file exists and is writable.
	       -x file		    file   exists  and	is  exe‐
				    cutable.
	       -a file		    file exists.
	       -e file		    file exists.
	       -f file		    file is a regular file.
	       -d file		    file is a directory.
	       -c file		    file is a character	 special
				    device.
	       -b file		    file   is  a  block	 special
				    device.
	       -p file		    file is a named pipe.
	       -u file		    file's mode has  setuid  bit
				    set.
	       -g file		    file's  mode  has setgid bit
				    set.
	       -k file		    file's mode has  sticky  bit
				    set.
	       -s file		    file is not empty.
	       -O file		    file's  owner is the shell's
				    effective user-ID.
	       -G file		    file's group is the	 shell's
				    effective group-ID.
	       -h file		    file is a symbolic link.
	       -H file		    file  is a context dependent
				    directory  (only  useful  on
				    HP-UX).
	       -L file		    file is a symbolic link.
	       -S file		    file is a socket.
	       -o option	    shell option is set (see set
				    command above  for	list  of
				    options).  As a non-standard
				    extension,	if  the	  option
				    starts with a !, the test is
				    negated;  the  test	  always
				    fails   if	 option	 doesn't
				    exist (thus
						  [ -o foo -o -o
						  !foo ]
					   returns  true  if and
					   only	 if  option  foo
					   exists).
	       file -nt file	    first  file	 is  newer  than
				    second file	 or  first  file
				    exists  and	 the second file
				    does not.
	       file -ot file	    first  file	 is  older  than
				    second  file  or second file
				    exists and	the  first  file
				    does not.

	       file -ef file	    first  file is the same file
				    as second file.
	       -t [fd]		    file  descriptor  is  a  tty
				    device.  If the posix option
				    (set  -o  posix,  see  POSIX
				    Mode  above)  is not set, fd
				    may be left	 out,  in  which
				    case  it  is  taken	 to be 1
				    (the behaviour  differs  due
				    to	the  special POSIX rules
				    described below).
	       string		    string is not empty.
	       -z string	    string is empty.
	       -n string	    string is not empty.
	       string = string	    strings are equal.
	       string == string	    strings are equal.
	       string != string	    strings are not equal.
	       number -eq number    numbers compare equal.
	       number -ne number    numbers compare not equal.
	       number -ge number    numbers compare greater than
				    or equal.
	       number -gt number    numbers    compare	 greater
				    than.
	       number -le number    numbers compare less than or
				    equal.
	       number -lt number    numbers compare less than.

	      The  above  basic	 expressions,  in  which  unary operators have
	      precedence over binary operators, may be combined with the  fol‐
	      lowing operators (listed in increasing order of precedence):

	       expr -o expr    logical or
	       expr -a expr    logical and
	       ! expr	       logical not
	       ( expr )	       grouping

	      On  operating  systems not supporting /dev/fd/n devices (where n
	      is a file descriptor number), the test command will  attempt  to
	      fake  it	for  all  tests	 that  operate on files (except the -e
	      test).  I.e., [ -w /dev/fd/2 ] tests if  file  descriptor	 2  is
	      writable.

	      Note  that some special rules are applied (courtesy of POSIX) if
	      the number of arguments to test or [ ... ] is less than five: if
	      leading  ! arguments can be stripped such that only one argument
	      remains then a string length test is performed (again,  even  if
	      the argument is a unary operator); if leading ! arguments can be
	      stripped such that three arguments remain and the	 second	 argu‐
	      ment  is	a  binary  operator, then the binary operation is per‐
	      formed (even if first argument is a unary operator, including an
	      unstripped !).

	      Note:  A	common mistake is to use if [ $foo = bar ] which fails
	      if parameter foo is null or unset, if  it	 has  embedded	spaces
	      (i.e.,  IFS  characters), or if it is a unary operator like ! or
	      -n.  Use tests like if [ "X$foo" = Xbar ] instead.

       time [-p] [ pipeline ]
	      If a pipeline is given, the times used to execute	 the  pipeline
	      are reported.  If no pipeline is given, then the user and system
	      time used by the shell itself, and all the commands it  has  run
	      since  it was started, are reported.  The times reported are the
	      real time (elapsed time from start to finish), the user cpu time
	      (time  spent running in user mode) and the system cpu time (time
	      spent running in kernel mode).  Times are reported  to  standard
	      error; the format of the output is:
		  0.00s real	 0.00s user	0.00s system
	      unless  the  -p  option is given (only possible if pipeline is a
	      simple command), in which case the output is slightly longer:
		  real	 0.00
		  user	 0.00
		  sys	 0.00
	      (the number of digits after the decimal may vary from system  to
	      system).	Note that simple redirections of standard error do not
	      effect the output of the time command:
				   time sleep 1 2> afile
				 { time sleep 1; } 2> afile
	      times for the first command do not go to afile, but those of the
	      second command do.

       times  Print  the  accumulated  user and system times used by the shell
	      and by processes which have exited that the shell started.

       trap [handler signal ...]
	      Sets trap handler that is to be executed when any of the	speci‐
	      fied  signals  are  received.   Handler is either a null string,
	      indicating the signals are to be ignored, a minus (-),  indicat‐
	      ing  that the default action is to be taken for the signals (see
	      signal(2 or 3)), or a string containing  shell  commands	to  be
	      evaluated	 and executed at the first opportunity (i.e., when the
	      current command completes,  or  before  printing	the  next  PS1
	      prompt) after receipt of one of the signals.  Signal is the name
	      of a signal (e.g., PIPE or ALRM) or the  number  of  the	signal
	      (see  kill  -l  command  above).	There are two special signals:
	      EXIT (also known as 0), which is	executed  when	the  shell  is
	      about  to	 exit, and ERR which is executed after an error occurs
	      (an error is something that would cause the shell to exit if the
	      -e  or  errexit  option were set — see set command above).  EXIT
	      handlers are executed in the environment of  the	last  executed
	      command.	Note that for non-interactive shells, the trap handler
	      cannot be changed for signals that were ignored when  the	 shell
	      started.

	      With no arguments, trap lists, as a series of trap commands, the
	      current state of the traps that have been set  since  the	 shell
	      started.	Note that the output of trap can not be usefully piped
	      to another process (an artifact  of  the	fact  that  traps  are
	      cleared when subprocesses are created).

	      The original Korn shell's DEBUG trap and the handling of ERR and
	      EXIT traps in functions are not yet implemented.

       true   A command that exits with a zero value.

       typeset [[±Ulprtux]  [-L[n]]  [-R[n]]  [-Z[n]]  [-i[n]]	|  -f  [-tux]]
       [name[=value] ...]
	      Display  or  set	parameter attributes.  With no name arguments,
	      parameter attributes are displayed: if no options arg used,  the
	      current attributes of all parameters are printed as typeset com‐
	      mands; if an option is given (or - with no  option  letter)  all
	      parameters  and  their  values with the specified attributes are
	      printed; if options are introduced with +, parameter values  are
	      not printed.

	      If name arguments are given, the attributes of the named parame‐
	      ters are set (-) or cleared  (+).	  Values  for  parameters  may
	      optionally  be specified.	 If typeset is used inside a function,
	      any newly created parameters are local to the function.

	      When -f is used, typeset operates on  the	 attributes  of	 func‐
	      tions.  As with parameters, if no names are given, functions are
	      listed with their values (i.e., definitions) unless options  are
	      introduced  with	+,  in	which case only the function names are
	      reported.

	       -Ln		 Left justify attribute: n specifies the field
				 width.	  If  n	 is not specified, the current
				 width of a parameter (or  the	width  of  its
				 first assigned value) is used.	 Leading white
				 space (and zeros, if used with the -Z option)
				 is stripped.  If necessary, values are either
				 truncated or space padded to  fit  the	 field
				 width.
	       -Rn		 Right	justify	 attribute:  n	specifies  the
				 field width.  If n is not specified, the cur‐
				 rent  width  of  a parameter (or the width of
				 its first assigned value) is used.   Trailing
				 white space are stripped.  If necessary, val‐
				 ues are either stripped of leading characters
				 or  space  padded  to make them fit the field
				 width.
	       -Zn		 Zero fill attribute: if not combined with -L,
				 this  is  the same as -R, except zero padding
				 is used instead of space padding.
	       -in		 integer attribute: n specifies	 the  base  to
				 use when displaying the integer (if not spec‐
				 ified, the base given in the first assignment
				 is used).  Parameters with this attribute may
				 be  assigned  values  containing   arithmetic
				 expressions.
	       -U		 unsigned   integer  attribute:	 integers  are
				 printed as unsigned values (only useful  when
				 combined with the -i option).	This option is
				 not in the original Korn shell.
	       -f		 Function mode: display or set	functions  and
				 their attributes, instead of parameters.
	       -l		 Lower case attribute: all  upper case charac‐
				 ters in values are converted to  lower	 case.
				 (In  the  original Korn shell, this parameter
				 meant `long integer' when used	 with  the  -i
				 option).
	       -p		 Print	complete  typeset commands that can be
				 used to re-create the attributes (but not the
				 values)  of  parameters.  This is the default
				 action (option exists for  ksh93  compatabil‐
				 ity).
	       -r		 Readonly  attribute: parameters with the this
				 attribute may not be assigned	to  or	unset.
				 Once  this  attribute	is  set, it can not be
				 turned off.
	       -t		 Tag attribute: has no meaning to  the	shell;
				 provided for application use.

				 For  functions,  -t  is  the trace attribute.
				 When functions with the trace	attribute  are
				 executed,  the	 xtrace	 (-x)  shell option is
				 temporarily turned on.
	       -u		 Upper case attribute: all lower case  charac‐
				 ters  in  values are converted to upper case.
				 (In the original Korn shell,  this  parameter
				 meant	`unsigned  integer' when used with the
				 -i option, which  meant  upper	 case  letters
				 would	never  be  used for bases greater than
				 10.  See the -U option).

				 For functions, -u is the undefined attribute.
				 See  Functions	 above for the implications of
				 this.
	       -x		 Export attribute: parameters  (or  functions)
				 are placed in the environment of any executed
				 commands.  Exported functions are not	imple‐
				 mented yet.

       ulimit [-acdfHlmnpsStvw] [value]
	      Display or set process limits.  If no options are used, the file
	      size limit (-f) is assumed.  value, if specified, may be	either
	      be  an  arithmetic expression or the word unlimited.  The limits
	      affect the shell and any processes created by the shell after  a
	      limit  is	 imposed.  Note that some systems may not allow limits
	      to be increased once they are set.  Also note that the types  of
	      limits  available	 are system dependent - some systems have only
	      the -f limit.

	      -a     Displays all limits; unless -H is used, soft  limits  are
		     displayed.

	      -H     Set  the hard limit only (default is to set both hard and
		     soft limits).

	      -S     Set the soft limit only (default is to set both hard  and
		     soft limits).

	      -c     Impose  a	size  limit  of	 n  blocks on the size of core
		     dumps.

	      -d     Impose a size limit of n kbytes on the size of  the  data
		     area.

	      -f     Impose  a	size limit of n blocks on files written by the
		     shell and its child processes (files of any size  may  be
		     read).

	      -l     Impose  a	limit  of  n  kbytes  on  the amount of locked
		     (wired) physical memory.

	      -m     Impose a limit of n kbytes on the amount of physical mem‐
		     ory used.

	      -n     Impose  a limit of n file descriptors that can be open at
		     once.

	      -p     Impose a limit of n processes that can be run by the user
		     at any one time.

	      -s     Impose  a size limit of n kbytes on the size of the stack
		     area.

	      -t     Impose a time limit of n cpu seconds to be used  by  each
		     process.

	      -v     Impose  a limit of n kbytes on the amount of virtual mem‐
		     ory used; on some systems this is the  maximum  allowable
		     virtual address (in bytes, not kbytes).

	      -w     Impose  a	limit  of n kbytes on the amount of swap space
		     used.

	      As far as ulimit is concerned, a block is 512 bytes.

       umask [-S] [mask]
	      Display or set the file permission creation mask, or umask  (see
	      umask(2)).   If the -S option is used, the mask displayed or set
	      is symbolic, otherwise it is an octal number.

	      Symbolic masks are like those used by chmod(1):
		     [ugoa]{{=+-}{rwx}*}+[,...]
	      in which the first group of characters is the who part, the sec‐
	      ond  group  is the op part, and the last group is the perm part.
	      The who part specifies which part of the umask is	 to  be	 modi‐
	      fied.  The letters mean:

		     u	    the user permissions

		     g	    the group permissions

		     o	    the other permissions (non-user, non-group)

		     a	    all permissions (user, group and other)

	      The  op  part  indicates how the who permissions are to be modi‐
	      fied:

		     =	    set

		     +	    added to

		     -	    removed from

	      The perm part specifies which permissions are to be  set,	 added
	      or removed:

		     r	    read permission

		     w	    write permission

		     x	    execute permission

	      When symbolic masks are used, they describe what permissions may
	      be made available (as opposed to octal masks in which a set  bit
	      means  the  corresponding	 bit  is  to  be  cleared).   Example:
	      `ug=rwx,o=' sets	the  mask  so  files  will  not	 be  readable,
	      writable	or  executable by `others', and is equivalent (on most
	      systems) to the octal mask `07'.

       unalias [-adt] [name1 ...]
	      The aliases for the given names are removed.  If the  -a	option
	      is  used,	 all aliases are removed.  If the -t or -d options are
	      used, the indicated operations are carried  out  on  tracked  or
	      directory aliases, respectively.

       unset [-fv] parameter ...
	      Unset  the named parameters (-v, the default) or functions (-f).
	      The exit status is  non-zero  if	any  of	 the  parameters  were
	      already unset, zero otherwise.

       wait [job]
	      Wait  for	 the  specified	 job(s) to finish.  The exit status of
	      wait is that of the last specified  job:	if  the	 last  job  is
	      killed  by  a signal, the exit status is 128 + the number of the
	      signal (see kill -l exit-status above); if  the  last  specified
	      job  can't  be  found  (because it never existed, or had already
	      finished), the exit status of wait  is  127.   See  Job  Control
	      below  for  the format of job.  Wait will return if a signal for
	      which a trap has been set is received, or if a HUP, INT or  QUIT
	      signal is received.

	      If  no  jobs are specified, wait waits for all currently running
	      jobs (if any) to finish and exits with a zero  status.   If  job
	      monitoring  is enabled, the completion status of jobs is printed
	      (this is not the case when jobs are explicitly specified).

       whence [-pv] [name ...]
	      For each name, the type of command  is  listed  (reserved	 word,
	      built-in, alias, function, tracked alias or executable).	If the
	      -p option is used, a path search done even if name is a reserved
	      word,  alias,  etc.  Without the -v option, whence is similar to
	      command -v except that whence will find reserved words and won't
	      print  aliases  as alias commands; with the -v option, whence is
	      the same as command -V.  Note that for  whence,  the  -p	option
	      does  not	 affect	 the search path used, as it does for command.
	      If the type of one or more of the names could not be determined,
	      the exit status is non-zero.

   Job Control
       Job  control refers to the shell's ability to monitor and control jobs,
       which are processes or groups of	 processes  created  for  commands  or
       pipelines.   At	a  minimum, the shell keeps track of the status of the
       background (i.e., asynchronous) jobs that currently exist; this	infor‐
       mation  can  be	displayed  using  the jobs command.  If job control is
       fully enabled (using set -m or set -o monitor), as it is	 for  interac‐
       tive  shells,  the  processes  of a job are placed in their own process
       group, foreground jobs can be stopped by typing the  suspend  character
       from  the  terminal  (normally ^Z), jobs can be restarted in either the
       foreground or background, using the fg and bg  commands,	 respectively,
       and  the	 state	of the terminal is saved or restored when a foreground
       job is stopped or restarted, respectively.

       Note that only commands that create processes (e.g., asynchronous  com‐
       mands,  subshell commands, and non-built-in, non-function commands) can
       be stopped; commands like read cannot be.

       When a job is created, it is assigned a	job-number.   For  interactive
       shells, this number is printed inside [..], followed by the process-ids
       of the processes in the job when an asynchronous command is run.	 A job
       may  be	referred  to in bg, fg, jobs, kill and wait commands either by
       the process id of the last process in the command pipeline  (as	stored
       in the $! parameter) or by prefixing the job-number with a percent sign
       (%).  Other percent sequences can also be used to refer to jobs:

	%+			 The most recently stopped job, or,  if	 there
				 are no stopped jobs, the oldest running job.
	%%, %			 Same as %+.
	%-			 The  job  that	 would	be  the %+ job, if the
				 later did not exist.
	%n			 The job with job-number n.
	%?string		 The job  containing  the  string  string  (an
				 error occurs if multiple jobs are matched).
	%string			 The job starting with string string (an error
				 occurs if multiple jobs are matched).

       When a job changes state (e.g., a background job finishes or foreground
       job is stopped), the shell prints the following status information:
	      [number] flag status command
       where

	number
	      is the job-number of the job.

	flag  is + or - if the job is the %+ or %- job, respectively, or space
	      if it is neither.

	status
	      indicates the current state of the job and can be

	      Running
		     the job has neither stopped or exited (note that  running
		     does  not	necessarily  mean  consuming  CPU  time	 — the
		     process could be blocked waiting for some event).

	      Done [(number)]
		     the job exited. number is the exit	 status	 of  the  job,
		     which is omitted if the status is zero.

	      Stopped [(signal)]
		     the job was stopped by the indicated signal (if no signal
		     is given, the job was stopped by SIGTSTP).

	      signal-description [(core dumped)]
		     the job was  killed  by  a	 signal	 (e.g.,	 Memory fault,
		     Hangup,  etc. — use kill -l for a list of signal descrip‐
		     tions).  The (core dumped) message indicates the  process
		     created a core file.

	command
	      is  the command that created the process.	 If there are multiple
	      processes in the job, then each process will have a line showing
	      its command and possibly its status, if it is different from the
	      status of the previous process.

       When an attempt is made to exit the shell while there are jobs  in  the
       stopped state, the shell warns the user that there are stopped jobs and
       does not exit.  If another attempt is  immediately  made	 to  exit  the
       shell,  the  stopped  jobs  are	sent a HUP signal and the shell exits.
       Similarly, if the nohup option is not set and there  are	 running  jobs
       when an attempt is made to exit a login shell, the shell warns the user
       and does not exit.  If another attempt is immediately made to exit  the
       shell, the running jobs are sent a HUP signal and the shell exits.

   Interactive Input Line Editing
       The  shell  supports three modes of reading command lines from a tty in
       an interactive session.	Which is used  is  controlled  by  the	emacs,
       gmacs and vi set options (at most one of these can be set at once).  If
       none of these options is enabled, the shell simply  reads  lines	 using
       the  normal tty driver.	If the emacs or gmacs option is set, the shell
       allows emacs like editing of the command; similarly, if the  vi	option
       is  set,	 the shell allows vi like editing of the command.  These modes
       are described in detail in the following sections.

       In these editing modes, if a line is longer that the screen width  (see
       COLUMNS parameter), a >, + or < character is displayed in the last col‐
       umn indicating that there are more characters after, before and	after,
       or  before  the	current	 position, respectively.  The line is scrolled
       horizontally as necessary.

   Emacs Editing Mode
       When the emacs  option  is  set,	 interactive  input  line  editing  is
       enabled.	  Warning: This mode is slightly different from the emacs mode
       in the original Korn shell and the 8th bit is stripped in  emacs	 mode.
       In  this	 mode various editing commands (typically bound to one or more
       control characters) cause immediate actions without waiting for a  new-
       line.  Several editing commands are bound to particular control charac‐
       ters when the shell is invoked; these bindings can be changed using the
       following commands:

       bind   The current bindings are listed.

       bind string=[editing-command]
	      The  specified  editing  command	is  bound to the given string,
	      which should consist of a control character (which may be	 writ‐
	      ten  using caret notation ^X), optionally preceded by one of the
	      two prefix characters.  Future input of the  string  will	 cause
	      the  editing  command  to	 be  immediately  invoked.   Note that
	      although only two prefix characters (usually  ESC	 and  ^X)  are
	      supported, some multi-character sequences can be supported.  The
	      following binds the arrow keys on an  ANSI  terminal,  or	 xterm
	      (these  are  in  the  default  bindings).	 Of course some escape
	      sequences won't work out quite this nicely:

	      bind '^[['=prefix-2
	      bind '^XA'=up-history
	      bind '^XB'=down-history
	      bind '^XC'=forward-char
	      bind '^XD'=backward-char

       bind -l
	      Lists the names of the functions to which keys may be bound.

       bind -m string=[substitute]
	      The  specified  input  string  will  afterwards  be  immediately
	      replaced by the given substitute string, which may contain edit‐
	      ing commands.

       The following is a list of editing commands available.	Each  descrip‐
       tion  starts  with  the name of the command, a n, if the command can be
       prefixed with a count, and any keys the command is bound to by  default
       (written	 using caret notation, e.g., ASCII ESC character is written as
       ^[).  A count prefix for a command is entered using the	sequence  ^[n,
       where  n is a sequence of 1 or more digits; unless otherwise specified,
       if a count is omitted, it defaults to 1.	  Note	that  editing  command
       names  are  used only with the bind command.  Furthermore, many editing
       commands are useful only on  terminals  with  a	visible	 cursor.   The
       default	bindings were chosen to resemble corresponding EMACS key bind‐
       ings.  The users tty characters (e.g., ERASE) are bound	to  reasonable
       substitutes and override the default bindings.

       abort ^G
	      Useful  as  a response to a request for a search-history pattern
	      in order to abort the search.

       auto-insert n
	      Simply causes the character to appear as	literal	 input.	  Most
	      ordinary characters are bound to this.

       backward-char  n ^B
	      Moves the cursor backward n characters.

       backward-word  n ^[B
	      Moves the cursor backward to the beginning of a word; words con‐
	      sist of alphanumerics, underscore (_) and dollar ($).

       beginning-of-history ^[<
	      Moves to the beginning of the history.

       beginning-of-line ^A
	      Moves the cursor to the beginning of the edited input line.

       capitalize-word n ^[c, ^[C
	      Uppercase the first character in the next n words,  leaving  the
	      cursor  past the end of the last word.  If the current line does
	      not begin with a comment character, one is added at  the	begin‐
	      ning  of the line and the line is entered (as if return had been
	      pressed), otherwise the existing comment characters are  removed
	      and the cursor is placed at the beginning of the line.

       complete ^[^[
	      Automatically completes as much as is unique of the command name
	      or the file name containing the cursor.  If the entire remaining
	      command or file name is unique a space is printed after its com‐
	      pletion, unless it is a  directory  name	in  which  case	 /  is
	      appended.	  If there is no command or file name with the current
	      partial word as its prefix, a bell character is output  (usually
	      causing a audio beep).

       complete-command ^X^[
	      Automatically completes as much as is unique of the command name
	      having the partial word up to the cursor as its  prefix,	as  in
	      the complete command described above.

       complete-file ^[^X
	      Automatically  completes	as  much as is unique of the file name
	      having the partial word up to the cursor as its  prefix,	as  in
	      the complete command described above.

       complete-list ^[=
	      List the possible completions for the current word.

       delete-char-backward n ERASE, ^?, ^H
	      Deletes n characters before the cursor.

       delete-char-forward n
	      Deletes n characters after the cursor.

       delete-word-backward n ^[ERASE, ^[^?, ^[^H, ^[h
	      Deletes n words before the cursor.

       delete-word-forward n ^[d
	      Deletes characters after the cursor up to the end of n words.

       down-history n ^N
	      Scrolls  the history buffer forward n lines (later).  Each input
	      line originally starts just after the last entry in the  history
	      buffer,  so  down-history is not useful until either search-his‐
	      tory or up-history has been performed.

       downcase-word n ^[L, ^[l
	      Lowercases the next n words.

       end-of-history ^[>
	      Moves to the end of the history.

       end-of-line ^E
	      Moves the cursor to the end of the input line.

       eot ^_ Acts as an end-of-file; this is useful because  edit-mode	 input
	      disables normal terminal input canonicalization.

       eot-or-delete n ^D
	      Acts  as	eot if alone on a line; otherwise acts as delete-char-
	      forward.

       error  Error (ring the bell).

       exchange-point-and-mark ^X^X
	      Places the cursor where the mark is, and sets the mark to	 where
	      the cursor was.

       expand-file ^[*
	      Appends  a  * to the current word and replaces the word with the
	      result of performing file globbing on the	 word.	 If  no	 files
	      match the pattern, the bell is rung.

       forward-char n ^F
	      Moves the cursor forward n characters.

       forward-word n ^[f
	      Moves the cursor forward to the end of the nth word.

       goto-history n ^[g
	      Goes to history number n.

       kill-line KILL
	      Deletes the entire input line.

       kill-region ^W
	      Deletes the input between the cursor and the mark.

       kill-to-eol n ^K
	      Deletes the input from the cursor to the end of the line if n is
	      not specified, otherwise deletes characters between  the	cursor
	      and column n.

       list ^[?
	      Prints  a sorted, columnated list of command names or file names
	      (if any) that can complete the partial word containing the  cur‐
	      sor.  Directory names have / appended to them.

       list-command ^X?
	      Prints  a sorted, columnated list of command names (if any) that
	      can complete the partial word containing the cursor.

       list-file ^X^Y
	      Prints a sorted, columnated list of file names (if any) that can
	      complete	the  partial  word  containing	the cursor.  File type
	      indicators are appended as described under list above.

       newline ^J, ^M
	      Causes the current input line to be processed by the shell.  The
	      current cursor position may be anywhere on the line.

       newline-and-next ^O
	      Causes  the current input line to be processed by the shell, and
	      the next line from history becomes the current  line.   This  is
	      only useful after an up-history or search-history.

       no-op QUIT
	      This does nothing.

       prefix-1 ^[
	      Introduces a 2-character command sequence.

       prefix-2 ^X

       prefix-2 ^[[
	      Introduces a 2-character command sequence.

       prev-hist-word n ^[., ^[_
	      The  last	 (nth) word of the previous command is inserted at the
	      cursor.

       quote ^^
	      The following character is taken literally  rather  than	as  an
	      editing command.

       redraw ^L
	      Reprints the prompt string and the current input line.

       search-character-backward n ^[^]
	      Search backward in the current line for the nth occurance of the
	      next character typed.

       search-character-forward n ^]
	      Search forward in the current line for the nth occurance of  the
	      next character typed.

       search-history ^R
	      Enter  incremental  search  mode.	  The internal history list is
	      searched backwards for commands matching the input.  An  initial
	      ^	 in  the search string anchors the search.  The abort key will
	      leave search mode.  Other commands will be executed after	 leav‐
	      ing  search  mode.   Successive search-history commands continue
	      searching backward to the next previous occurrence of  the  pat‐
	      tern.  The history buffer retains only a finite number of lines;
	      the oldest are discarded as necessary.

       set-mark-command ^[<space>
	      Set the mark at the cursor position.

       stuff  On systems supporting it, pushes the bound character  back  onto
	      the  terminal  input  where it may receive special processing by
	      the terminal handler.  This is useful for the BRL ^T mini-systat
	      feature, for example.

       stuff-reset
	      Acts like stuff, then aborts input the same as an interrupt.

       transpose-chars ^T
	      If  at  the  end	of  line,  or if the gmacs option is set, this
	      exchanges the two previous characters; otherwise,	 it  exchanges
	      the  previous  and  current  characters and moves the cursor one
	      character to the right.

       up-history n ^P
	      Scrolls the history buffer backward n lines (earlier).

       upcase-word n ^[U, ^[u
	      Uppercases the next n words.

       version ^V
	      Display the version of ksh.  The current edit buffer is restored
	      as soon as any key is pressed (the key is then processed, unless
	      it is a space).

       yank ^Y
	      Inserts the most recently killed text string at the current cur‐
	      sor position.

       yank-pop ^[y
	      Immediately after a yank, replaces the inserted text string with
	      the next previous killed text string.

   Vi Editing Mode
       The vi command line editor in ksh has basically the  same  commands  as
       the vi editor (see vi(1)), with the following exceptions:

	 ·    you start out in insert mode,

	 ·    there  are  file	name and command completion commands (=, \, *,
	      ^X, ^E, ^F and, optionally, <tab>),

	 ·    the _ command is different (in ksh it is the last argument  com‐
	      mand, in vi it goes to the start of the current line),

	 ·    the  /  and  G  commands move in the opposite direction as the j
	      command

	 ·    and commands which don't make sense in a single line editor  are
	      not  available  (e.g.,  screen movement commands, ex : commands,
	      etc.).

       Note that the ^X stands for control-X; also <esc>,  <space>  and	 <tab>
       are used for escape, space and tab, respectively (no kidding).

       Like  vi, there are two modes: insert mode and command mode.  In insert
       mode, most characters are simply put in the buffer at the current  cur‐
       sor  position  as  they are typed, however, some characters are treated
       specially.  In particular, the following characters are taken from cur‐
       rent  tty  settings  (see stty(1)) and have their usual meaning (normal
       values are in parentheses): kill (^U), erase  (^?),  werase  (^W),  eof
       (^D), intr (^C) and quit (^\).  In addition to the above, the following
       characters are also treated specially in insert mode:

	^H			 erases previous character
	^V			 literal next: the next character typed is not
				 treated  specially (can be used to insert the
				 characters being described here)
	^J ^M			 end of line: the current line is read, parsed
				 and executed by the shell
	<esc>			 puts the editor in command mode (see below)
	^E			 command and file name enumeration (see below)
	^F			 command and file name completion (see below).
				 If used twice in a row, the list of  possible
				 completions  is  displayed;  if  used a third
				 time, the completion is undone.
	^X			 command and file name expansion (see below)
	<tab>			 optional file	name  and  command  completion
				 (see  ^F  above), enabled with set -o vi-tab‐
				 complete

       In command mode, each character is interpreted as a  command.   Charac‐
       ters  that  don't  correspond  to commands, are illegal combinations of
       commands or are commands that can't be carried out all cause beeps.  In
       the  following  command	descriptions, a n indicates the command may be
       prefixed by a number (e.g., 10l moves right 10 characters); if no  num‐
       ber  prefix  is	used, n is assumed to be 1 unless otherwise specified.
       The term `current position' refers to the position between  the	cursor
       and the character preceding the cursor.	A `word' is a sequence of let‐
       ters, digits and underscore characters or  a  sequence  of  non-letter,
       non-digit,  non-underscore,  non-white-space  characters	 (e.g., ab2*&^
       contains two words) and a `big-word' is a sequence  of  non-white-space
       characters.

       Special ksh vi commands
	      The  following  commands	are not in, or are different from, the
	      normal vi file editor:

	      n_     insert a space followed by the nth big-word from the last
		     command  in the history at the current position and enter
		     insert mode; if n is not  specified,  the	last  word  is
		     inserted.

	      #	     insert the comment character (#) at the start of the cur‐
		     rent line and return the line to the shell (equivalent to
		     I#^J).

	      ng     like G, except if n is not specified, it goes to the most
		     recent remembered line.

	      nv     edit line n using the vi editor; if n is  not  specified,
		     the  current line is edited.  The actual command executed
		     is `fc -e ${VISUAL:-${EDITOR:-vi}} n'.

	      * and ^X
		     command or file name expansion is applied to the  current
		     big-word  (with  an  appended  *, if the word contains no
		     file globing characters) - the big-word is replaced  with
		     the  resulting  words.   If  the  current big-word is the
		     first on the line (or follows one of the following	 char‐
		     acters:  ;,  |, &, (, )) and does not contain a slash (/)
		     then command  expansion  is  done,	 otherwise  file  name
		     expansion is done.	 Command expansion will match the big-
		     word against all aliases, functions and built-in commands
		     as	 well  as  any executable files found by searching the
		     directories in the PATH parameter.	 File  name  expansion
		     matches  the  big-word  against  the files in the current
		     directory.	 After expansion, the cursor  is  placed  just
		     past the last word and the editor is in insert mode.

	      n\, n^F, n<tab> and n<esc>
		     command/file  name	 completion:  replace the current big-
		     word with the longest unique match	 obtained  after  per‐
		     forming  command/file name expansion.  <tab> is only rec‐
		     ognized if the vi-tabcomplete option is set, while	 <esc>
		     is	 only  recognized  if the vi-esccomplete option is set
		     (see set -o).  If n is specified, the nth	possible  com‐
		     pletion is selected (as reported by the command/file name
		     enumeration command).

	      = and ^E
		     command/file name enumeration: list all the  commands  or
		     files that match the current big-word.

	      ^V     display  the  version  of	pdksh;	it  is displayed until
		     another key is pressed (this key is ignored).

	      @c     macro expansion: execute the commands found in the	 alias
		     _c.

       Intra-line movement commands

	      nh and n^H
		     move left n characters.

	      nl and n<space>
		     move right n characters.

	      0	     move to column 0.

	      ^	     move to the first non white-space character.

	      n|     move to column n.

	      $	     move to the last character.

	      nb     move back n words.

	      nB     move back n big-words.

	      ne     move forward to the end the word, n times.

	      nE     move forward to the end the big-word, n times.

	      nw     move forward n words.

	      nW     move forward n big-words.

	      %	     find  match:  the	editor	looks  forward for the nearest
		     parenthesis, bracket or brace and then moves the  to  the
		     matching parenthesis, bracket or brace.

	      nfc    move forward to the nth occurrence of the character c.

	      nFc    move backward to the nth occurrence of the character c.

	      ntc    move  forward  to	just  before the nth occurrence of the
		     character c.

	      nTc    move backward to just before the nth  occurrence  of  the
		     character c.

	      n;     repeats the last f, F, t or T command.

	      n,     repeats  the  last f, F, t or T command, but moves in the
		     opposite direction.

       Inter-line movement commands

	      nj and n+ and n^N
		     move to the nth next line in the history.

	      nk and n- and n^P
		     move to the nth previous line in the history.

	      nG     move to line n in the history; if n is not specified, the
		     number first remembered line is used.

	      ng     like G, except if n is not specified, it goes to the most
		     recent remembered line.

	      n/string
		     search backward through the history for the nth line con‐
		     taining string; if string starts with ^, the remainder of
		     the string must appear at the start of the	 history  line
		     for it to match.

	      n?string
		     same  as  /,  except it searches forward through the his‐
		     tory.

	      nn     search for the nth occurrence of the last search  string;
		     the  direction  of	 the  search  is  the same as the last
		     search.

	      nN     search for the nth occurrence of the last search  string;
		     the  direction  of the search is the opposite of the last
		     search.

       Edit commands

	      na     append text n times: goes into insert mode just after the
		     current  position.	 The append is only replicated if com‐
		     mand mode is re-entered (i.e., <esc> is used).

	      nA     same as a, except it appends at the end of the line.

	      ni     insert text n times: goes into insert mode at the current
		     position.	 The  insertion	 is only replicated if command
		     mode is re-entered (i.e., <esc> is used).

	      nI     same as i, except the insertion is done just  before  the
		     first non-blank character.

	      ns     substitute	 the next n characters (i.e., delete the char‐
		     acters and go into insert mode).

	      S	     substitute whole line: all characters from the first non-
		     blank character to the end of line are deleted and insert
		     mode is entered.

	      ncmove-cmd
		     change from the current position to the position  result‐
		     ing  from	n move-cmds (i.e., delete the indicated region
		     and go into insert mode); if  move-cmd  is	 c,  the  line
		     starting from the first non-blank character is changed.

	      C	     change  from  the current position to the end of the line
		     (i.e., delete to the end of the line and go  into	insert
		     mode).

	      nx     delete the next n characters.

	      nX     delete the previous n characters.

	      D	     delete to the end of the line.

	      ndmove-cmd
		     delete  from the current position to the position result‐
		     ing from n move-cmds; move-cmd is a movement command (see
		     above) or d, in which case the current line is deleted.

	      nrc    replace the next n characters with the character c.

	      nR     replace: enter insert mode but overwrite existing charac‐
		     ters instead of  inserting	 before	 existing  characters.
		     The replacement is repeated n times.

	      n~     change the case of the next n characters.

	      nymove-cmd
		     yank  from the current position to the position resulting
		     from n move-cmds into the yank buffer; if move-cmd is  y,
		     the whole line is yanked.

	      Y	     yank from the current position to the end of the line.

	      np     paste the contents of the yank buffer just after the cur‐
		     rent position, n times.

	      nP     same as p, except the buffer is  pasted  at  the  current
		     position.

       Miscellaneous vi commands

	      ^J and ^M
		     the  current  line	 is  read,  parsed and executed by the
		     shell.

	      ^L and ^R
		     redraw the current line.

	      n.     redo the last edit command n times.

	      u	     undo the last edit command.

	      U	     undo all changes that have been made to the current line.

	      intr and quit
		     the interrupt and quit terminal characters cause the cur‐
		     rent line to be deleted and a new prompt to be printed.

FILES
       ~/.profile
       /etc/profile
       /etc/suid_profile

BUGS
       Any  bugs  in  pdksh  should  be	 reported  to pdksh@cs.mun.ca.	Please
       include the version of pdksh (echo $KSH_VERSION shows it), the machine,
       operating system and compiler you are using and a description of how to
       repeat the bug (a small shell  script  that  demonstrates  the  bug  is
       best).  The following, if relevant (if you are not sure, include them),
       can also helpful: options you are using (both options.h options and set
       -o options) and a copy of your config.h (the file generated by the con‐
       figure  script).	  New  versions	 of  pdksh  can	  be   obtained	  from
       ftp://ftp.cs.mun.ca/pub/pdksh/.

       BTW, the most frequently reported bug is
	       echo hi | read a; echo $a   # Does not print hi
       I'm aware of this and there is no need to report it.

VERSION
       This page documents version
			    @(#)PD KSH v5.2.14 99/07/13.2
       of the public domain korn shell.

AUTHORS
       This shell is based on the public domain 7th edition Bourne shell clone
       by Charles Forsyth and parts of the BRL shell by	 Doug  A.  Gwyn,  Doug
       Kingston,  Ron  Natalie,	 Arnold	 Robbins, Lou Salkind and others.  The
       first release of pdksh was created by Eric Gisin,  and  it  was	subse‐
       quently	maintained  by	John R. MacMillan (chance!john@sq.sq.com), and
       Simon J.	 Gerraty  (sjg@zen.void.oz.au).	  The  current	maintainer  is
       Michael	Rendell	 (michael@cs.mun.ca).	The  CONTRIBUTORS  file in the
       source distribution contains a more complete list of people  and	 their
       part in the shell's development.

SEE ALSO
       awk(1),	sh(1),	csh(1), ed(1), getconf(1), getopt(1), sed(1), stty(1),
       vi(1),  dup(2),	execve(2),  getgid(2),	getuid(2),  open(2),  pipe(2),
       wait(2), getopt(3), rand(3), signal(3), system(3), environ(5)

       The KornShell Command and Programming Language, Morris Bolsky and David
       Korn, 1989, ISBN 0-13-516972-0.

       UNIX Shell Programming, Stephen G. Kochan, Patrick H. Wood, Hayden.

       IEEE Standard for information Technology -  Portable  Operating	System
       Interface  (POSIX)  - Part 2: Shell and Utilities, IEEE Inc, 1993, ISBN
       1-55937-255-9.

				August 19, 1996				KSH(1)
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