nohup(1)nohup(1)NAMEnohup - Runs a utility ignoring hangups and quits
SYNOPSISnohup utility [argument...]
Note
The C shell has a built-in version of the nohup command. If you are
using the C shell, and want to guarantee that you are using the command
described here, you must specify the full path /usr/bin/nohup. See the
csh(1) reference page for a description of the built-in command.
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
nohup: XCU5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
OPTIONS
None
OPERANDS
The name of a command to be invoked. Optional arguments required by
the utility specified for invokation.
DESCRIPTION
The nohup command runs utility, ignoring all hangups and QUIT signals.
You can use this command to run programs in the background after log‐
ging off the system. To run a nohup command in the background, add an
& (ampersand) to the end of the command.
If nohup output is redirected to a terminal or is not redirected at
all, the output is appended to the file nohup.out. If the file is cre‐
ated, the permission bits are set to Owner Read and Owner Write (600).
If nohup.out is not writable in the current directory, the output is
redirected to $HOME/nohup.out. If neither file can be created nor
opened for appending, utility is not invoked.
If standard error is a terminal, all output written to standard error
is appended to the file receiving standard output.
The nohup command accepts just one utility as an argument. To apply
nohup to a pipeline or list of commands, enter the pipeline or list in
a shell script file. Then run sh as utility using the following for‐
mat: nohup sh -c file
[Tru64 UNIX] You can also assign the shell file execute permission and
run it as the utility in the form: nohup file
NOTES
The term utility, rather than the term command, describes the argument
to nohup because shell compound commands, pipelines, special built-in
programs, and the like, cannot be handled directly. In addition, the
term utility includes user application programs and shell scripts, not
just the standard utilities.
EXIT STATUS
The nohup command returns the following exit values: The specified
utility was found, but could not be invoked. The error occurred in the
nohup utility or the specified utility could not be found.
The exit status is otherwise that of the utility.
EXAMPLES
To leave a command running after logging out (sh only), enter: nohup
find / -print &
Shortly after you enter this, the following is displayed: 670 $
Sending output to nohup.out
The process ID number changes to the background process started
by the & (ampersand), in this case, 670. The $ (dollar sign) is
the shell prompt. The message following informs you that the
output from the find command is in the file nohup.out. Sending
output...
You can log out after you see these messages, even if the find
command has not finished yet.
If you are using csh, the built-in command nohup is executed
instead of the system command. To execute the nohup system com‐
mand, you must enter an absolute path. To do the same, but re‐
direct the standard output to a different file, enter: nohup
find / -print >filenames &
This runs the find command and stores its output in a file named
filenames. Now only the process ID and prompt are displayed.
Wait for a second or two before logging out, because the nohup
command takes a moment to start the command you specified. If
you log out too quickly, utility may not run at all. Once util‐
ity has started, logging out does not affect it. To run more
than one command, use a shell script. For example, if you
include the following shell script: comm -23 fi4 fi5 | comm -23
- fi6 | join -a1 - fi7 > comm.out
and name it ncomm, you can run nohup for all of the commands in
ncomm by entering: nohup sh ncomm
If you assign ncomm Execute permission, you can obtain the same
results by issuing the command: nohup ncomm
To run this command in the background, enter: nohup ncomm &
ENVIRONMENT VARIABLES
The following environment variables affect the execution of nohup: Pro‐
vides a default value for the internationalization variables that are
unset or null. If LANG is unset or null, the corresponding value from
the default locale is used. If any of the internationalization vari‐
ables contain an invalid setting, the utility behaves as if none of the
variables had been defined. If set to a non-empty string value, over‐
rides the values of all the other internationalization variables.
Determines the locale for the interpretation of sequences of bytes of
text data as characters (for example, single-byte as opposed to multi‐
byte characters in arguments). Determines the locale for the format
and contents of diagnostic messages written to standard error. Deter‐
mines the location of message catalogues for the processing of LC_MES‐
SAGES. Determines the search path that will be used to locate the com‐
mand to be invoked.
FILES
Standard output and standard error file for nohup.
SEE ALSO
Commands: csh(1), ksh(1), nice(1), Bourne shell sh(1b), POSIX shell
sh(1p)
Functions: sigaction(2)
Standards: standards(5)nohup(1)