Sysadm::Install(3) User Contributed Perl Documentation Sysadm::Install(3)NAMESysadm::Install - Typical installation tasks for system administrators
SYNOPSIS
use Sysadm::Install qw(:all);
my $INST_DIR = '/home/me/install/';
cd($INST_DIR);
cp("/deliver/someproj.tgz", ".");
untar("someproj.tgz");
cd("someproj");
# Write out ...
blurt("Builder: Mike\nDate: Today\n", "build.dat");
# Slurp back in ...
my $data = slurp("build.dat");
# or edit in place ...
pie(sub { s/Today/scalar localtime()/ge; $_; }, "build.dat");
make("test install");
# run a cmd and tap into stdout and stderr
my($stdout, $stderr, $exit_code) = tap("ls", "-R");
DESCRIPTION
Have you ever wished for your installation shell scripts to run
reproducably, without much programming fuzz, and even with optional
logging enabled? Then give up shell programming, use Perl.
"Sysadm::Install" executes shell-like commands performing typical
installation tasks: Copying files, extracting tarballs, calling "make".
It has a "fail once and die" policy, meticulously checking the result
of every operation and calling "die()" immeditatly if anything fails.
"Sysadm::Install" also supports a dry_run mode, in which it logs
everything, but suppresses any write actions. Dry run mode is enabled
by calling Sysadm::Install::dry_run(1). To switch back to normal, call
Sysadm::Install::dry_run(0).
As of version 0.17, "Sysadm::Install" supports a confirm mode, in which
it interactively asks the user before running any of its functions
(just like "rm -i"). confirm mode is enabled by calling
Sysadm::Install::confirm(1). To switch back to normal, call
Sysadm::Install::confirm(0).
"Sysadm::Install" is fully Log4perl-enabled. To start logging, just
initialize "Log::Log4perl". "Sysadm::Install" acts as a wrapper class,
meaning that file names and line numbers are reported from the calling
program's point of view.
FUNCTIONS
"cp($source, $target)"
Copy a file from $source to $target. "target" can be a directory.
Note that "cp" doesn't copy file permissions. If you want the
target file to reflect the source file's user rights, use
"perm_cp()" shown below.
"mv($source, $target)"
Move a file from $source to $target. "target" can be a directory.
"download($url)"
Download a file specified by $url and store it under the name
returned by "basename($url)".
"untar($tarball)"
Untar the tarball in $tarball, which typically adheres to the
"someproject-X.XX.tgz" convention. But regardless of whether the
archive actually contains a top directory "someproject-X.XX", this
function will behave if it had one. If it doesn't have one, a new
directory is created before the unpacking takes place. Unpacks the
tarball into the current directory, no matter where the tarfile is
located. Please note that if you're using a compressed tarball
(.tar.gz or .tgz), you'll need IO::Zlib installed.
"untar_in($tar_file, $dir)"
Untar the tarball in $tgz_file in directory $dir. Create $dir if it
doesn't exist yet.
"pick($prompt, $options, $default)"
Ask the user to pick an item from a displayed list. $prompt is the
text displayed, $options is a referenc to an array of choices, and
$default is the number (starting from 1, not 0) of the default
item. For example,
pick("Pick a fruit", ["apple", "pear", "pineapple"], 3);
will display the following:
[1] apple
[2] pear
[3] pineapple
Pick a fruit [3]>
If the user just hits Enter, "pineapple" (the default value) will
be returned. Note that 3 marks the 3rd element of the list, and is
not an index value into the array.
If the user enters 1, 2 or 3, the corresponding text string
("apple", "pear", "pineapple" will be returned by "pick()".
"ask($prompt, $default)"
Ask the user to either hit Enter and select the displayed default
or to type in another string.
"mkd($dir)"
Create a directory of arbitrary depth, just like
"File::Path::mkpath".
"rmf($dir)"
Delete a directory and all of its descendents, just like "rm -rf"
in the shell.
"cd($dir)"
chdir to the given directory. If you don't want to have cd() modify
the internal directory stack (used for subsequent cdback() calls),
set the stack_update parameter to a false value:
cd($dir, {stack_update => 0});
"cdback()"
chdir back to the last directory before a previous "cd".
"make()"
Call "make" in the shell.
"pie($coderef, $filename, ...)"
Simulate "perl -pie 'do something' file". Edits files in-place.
Expects a reference to a subroutine as its first argument. It will
read out the file $filename line by line and calls the subroutine
setting a localized $_ to the current line. The return value of the
subroutine will replace the previous value of the line.
Example:
# Replace all 'foo's by 'bar' in test.dat
pie(sub { s/foo/bar/g; $_; }, "test.dat");
Works with one or more file names.
If the files are known to contain UTF-8 encoded data, and you want
it to be read/written as a Unicode strings, use the "utf8" option:
pie(sub { s/foo/bar/g; $_; }, "test.dat", { utf8 => 1 });
"plough($coderef, $filename, ...)"
Simulate "perl -ne 'do something' file". Iterates over all lines of
all input files and calls the subroutine provided as the first
argument.
Example:
# Print all lines containing 'foobar'
plough(sub { print if /foobar/ }, "test.dat");
Works with one or more file names.
If the files are known to contain UTF-8 encoded data, and you want
it to be read into Unicode strings, use the "utf8" option:
plough(sub { print if /foobar/ }, "test.dat", { utf8 => 1 });
"my $data = slurp($file, $options)"
Slurps in the file and returns a scalar with the file's content. If
called without argument, data is slurped from STDIN or from any
files provided on the command line (like <> operates).
If the file is known to contain UTF-8 encoded data and you want to
read it in as a Unicode string, use the "utf8" option:
my $unicode_string = slurp( $file, {utf8 => 1} );
"blurt($data, $file, $append)"
Opens a new file, prints the data in $data to it and closes the
file. If $append is set to a true value, data will be appended to
the file. Default is false, existing files will be overwritten.
If the string is a Unicode string, use the "utf8" option:
blurt( $unicode_string, $file, {utf8 => 1} );
"blurt_atomic($data, $file, $options)"
Write the data in $data to a file $file, guaranteeing that the
operation will either complete fully or not at all. This is
accomplished by first writing to a temporary file which is then
rename()ed to the target file.
Unlike in "blurt", there is no $append mode in "blurt_atomic".
If the string is a Unicode string, use the "utf8" option:
blurt_atomic( $unicode_string, $file, {utf8 => 1} );
"($stdout, $stderr, $exit_code) = tap($cmd, @args)"
Run a command $cmd in the shell, and pass it @args as args.
Capture STDOUT and STDERR, and return them as strings. If
$exit_code is 0, the command succeeded. If it is different, the
command failed and $exit_code holds its exit code.
Please note that "tap()" is limited to single shell commands, it
won't work with output redirectors ("ls >/tmp/foo" 2>&1).
In default mode, "tap()" will concatenate the command and args
given and create a shell command line by redirecting STDERR to a
temporary file. "tap("ls", "/tmp")", for example, will result in
'ls' '/tmp' 2>/tmp/sometempfile |
Note that all commands are protected by single quotes to make sure
arguments containing spaces are processed as singles, and no
globbing happens on wildcards. Arguments containing single quotes
or backslashes are escaped properly.
If quoting is undesirable, "tap()" accepts an option hash as its
first parameter,
tap({no_quotes => 1}, "ls", "/tmp/*");
which will suppress any quoting:
ls /tmp/* 2>/tmp/sometempfile |
Or, if you prefer double quotes, use
tap({double_quotes => 1}, "ls", "/tmp/$VAR");
wrapping all args so that shell variables are interpolated
properly:
"ls" "/tmp/$VAR" 2>/tmp/sometempfile |
Another option is "utf8" which runs the command in a terminal set
to UTF8.
Error handling: By default, tap() won't raise an error if the
command's return code is nonzero, indicating an error reported by
the shell. If bailing out on errors is requested to avoid return
code checking by the script, use the raise_error option:
tap({raise_error => 1}, "ls", "doesn't exist");
"$quoted_string = qquote($string, [$metachars])"
Put a string in double quotes and escape all sensitive characters
so there's no unwanted interpolation. E.g., if you have something
like
print "foo!\n";
and want to put it into a double-quoted string, it will look like
"print \"foo!\\n\""
Sometimes, not only backslashes and double quotes need to be
escaped, but also the target environment's meta chars. A string
containing
print "$<\n";
needs to have the '$' escaped like
"print \"\$<\\n\";"
if you want to reuse it later in a shell context:
$ perl -le "print \"\$<\\n\";"
1212
"qquote()" supports escaping these extra characters with its
second, optional argument, consisting of a string listing all
escapable characters:
my $script = 'print "$< rocks!\\n";';
my $escaped = qquote($script, '!$'); # Escape for shell use
system("perl -e $escaped");
=> 1212 rocks!
And there's a shortcut for shells: By specifying ':shell' as the
metacharacters string, qquote() will actually use '!$`'.
For example, if you wanted to run the perl code
print "foobar\n";
via
perl -e ...
on a box via ssh, you would use
use Sysadm::Installqw(qquote);
my $cmd = 'print "foobar!\n"';
$cmd = "perl -e " . qquote($cmd, ':shell');
$cmd = "ssh somehost " . qquote($cmd, ':shell');
print "$cmd\n";
system($cmd);
and get
ssh somehost "perl -e \"print \\\"foobar\\\!\\\\n\\\"\""
which runs on "somehost" without hickup and prints "foobar!".
Sysadm::Install comes with a script "one-liner" (installed in bin),
which takes arbitrary perl code on STDIN and transforms it into a
one-liner:
$ one-liner
Type perl code, terminate by CTRL-D
print "hello\n";
print "world\n";
^D
perl -e "print \"hello\\n\"; print \"world\\n\"; "
"$quoted_string = quote($string, [$metachars])"
Similar to "qquote()", just puts a string in single quotes and
escapes what needs to be escaped.
Note that shells typically don't support escaped single quotes
within single quotes, which means that
$ echo 'foo\'bar'
>
is invalid and the shell waits until it finds a closing quote.
Instead, there is an evil trick which gives the desired result:
$ echo 'foo'\''bar' # foo, single quote, \, 2 x single quote, bar
foo'bar
It uses the fact that shells interpret back-to-back strings as one.
The construct above consists of three back-to-back strings:
(1) 'foo'
(2) '
(3) 'bar'
which all get concatenated to a single
foo'bar
If you call "quote()" with $metachars set to ":shell", it will
perform that magic behind the scenes:
print quote("foo'bar");
# prints: 'foo'\''bar'
"perm_cp($src, $dst, ...)"
Read the $src file's user permissions and modify all $dst files to
reflect the same permissions.
"owner_cp($src, $dst, ...)"
Read the $src file/directory's owner uid and group gid and apply it
to $dst.
For example: copy uid/gid of the containing directory to a file
therein:
use File::Basename;
owner_cp( dirname($file), $file );
Usually requires root privileges, just like chown does.
"$perms = perm_get($filename)"
Read the $filename's user permissions and owner/group. Returns an
array ref to be used later when calling "perm_set($filename,
$perms)".
"perm_set($filename, $perms)"
Set file permissions and owner of $filename according to $perms,
which was previously acquired by calling "perm_get($filename)".
"sysrun($cmd)"
Run a shell command via "system()" and die() if it fails. Also
works with a list of arguments, which are then interpreted as
program name plus arguments, just like "system()" does it.
"hammer($cmd, $arg, ...)"
Run a command in the shell and simulate a user hammering the ENTER
key to accept defaults on prompts.
"say($text, ...)"
Alias for "print ..., "\n"", just like Perl6 is going to provide
it.
"sudo_me()"
Check if the current script is running as root. If yes, continue.
If not, restart the current script with all command line arguments
is restarted under sudo:
sudo scriptname args ...
Make sure to call this before any @ARGV-modifying functions like
"getopts()" have kicked in.
"bin_find($program)"
Search all directories in $PATH (the ENV variable) for an
executable named $program and return the full path of the first
hit. Returns "undef" if the program can't be found.
"fs_read_open($dir)"
Opens a file handle to read the output of the following process:
cd $dir; find ./ -xdev -print0 | cpio -o0 |
This can be used to capture a file system structure.
"fs_write_open($dir)"
Opens a file handle to write to a
| (cd $dir; cpio -i0)
process to restore a file system structure. To be used in
conjunction with fs_read_open.
"pipe_copy($in, $out, [$bufsize])"
Reads from $in and writes to $out, using sysread and syswrite. The
buffer size used defaults to 4096, but can be set explicitely.
"snip($data, $maxlen)"
Format the data string in $data so that it's only (roughly) $maxlen
characters long and only contains printable characters.
If $data is longer than $maxlen, it will be formatted like
(22)[abcdef[snip=11]stuvw]
indicating the length of the original string, the beginning, the
end, and the number of 'snipped' characters.
If $data is shorter than $maxlen, it will be returned unmodified
(except for unprintable characters replaced, see below).
If $data contains unprintable character's they are replaced by "."
(the dot).
"password_read($prompt)"
Reads in a password to be typed in by the user in noecho mode. A
call to password_read("password: ") results in
password: ***** (stars aren't actually displayed)
This function will switch the terminal back into normal mode after
the user hits the 'Return' key.
"nice_time($time)"
Format the time in a human-readable way, less wasteful than the
'scalar localtime' formatting.
print nice_time(), "\n";
# 2007/04/01 10:51:24
It uses the system time by default, but it can also accept epoch
seconds:
print nice_time(1170000000), "\n";
# 2007/01/28 08:00:00
It uses localtime() under the hood, so the outcome of the above
will depend on your local time zone setting.
"def_or($foo, $default)"
Perl-5.9 added the //= construct, which helps assigning values to
undefined variables. Instead of writing
if(!defined $foo) {
$foo = $default;
}
you can just write
$foo //= $default;
However, this is not available on older perl versions (although
there's source filter solutions). Often, people use
$foo ||= $default;
instead which is wrong if $foo contains a value that evaluates as
false. So Sysadm::Install, the everything-and-the-kitchen-sink
under the CPAN modules, provides the function "def_or()" which can
be used like
def_or($foo, $default);
to accomplish the same as
$foo //= $default;
How does it work, how does $foo get a different value, although
it's apparently passed in by value? Modifying $_[0] within the
subroutine is an old Perl trick to do exactly that.
"is_utf8_data($data)"
Check if the given string has the utf8 flag turned on. Works just
like Encode.pm's is_utf8() function, except that it silently
returns a false if Encode isn't available, for example when an
ancient perl without proper utf8 support is used.
"utf8_check($data)"
Check if we're using a perl with proper utf8 support, by verifying
the Encode.pm module is available for loading.
AUTHOR
Mike Schilli, <m@perlmeister.com>
COPYRIGHT AND LICENSE
Copyright (C) 2004-2007 by Mike Schilli
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself, either Perl version 5.8.3 or, at
your option, any later version of Perl 5 you may have available.
perl v5.14.1 2011-07-30 Sysadm::Install(3)
