nohup(1)

NAME

nohup — run a command immune to hangups

SYNOPSIS

nohup command [arguments]

DESCRIPTION

nohup executes command with hangups and quits ignored. If output is not redirected by the user, both standard output and standard error are sent to nohup.out. If nohup.out is not writable in the current directory, output is redirected to $HOME/nohup.out; otherwise, nohup fails. If a file is created, the file's permission bits will be set to S_IRUSR | S_IWUSR.

If output from nohup is redirected to a terminal, or is not redirected at all, the output is sent to nohup.out.

EXTERNAL INFLUENCES

Environment Variables

LC_MESSAGES determines the language in which messages are displayed.

If LC_MESSAGES is not specified in the environment or is set to the empty string, the value of LANG is used as a default for each unspecified or empty variable. If LANG is not specified or is set to the empty string, a default of "C" (see lang(5)) is used instead of LANG.

If any internationalization variable contains an invalid setting, nohup behaves as if all internationalization variables are set to "C". See environ(5).

International Code Set Support

Single- and multi-byte character code sets are supported.

EXAMPLES

It is frequently desirable to apply nohup to pipelines or lists of commands. This can be done only by placing pipelines and command lists in a single file, called a shell script. To run the script using nohup:

nohup sh file 

nohup features apply to the entire contents of file. If the shell script file is to be executed often, the need to type sh can be eliminated by setting execute permission on file. The script can also be run in the background with interrupts ignored (see sh(1)):

nohup file & 

file typically contains normal keyboard command sequences that one would want to continue running in case the terminal disconnects, such as:

tbl ofile | eqn | nroff > nfile 

WARNINGS

Be careful to place punctuation properly. For example, in the command form:

nohup command1; command2 

nohup applies only to command1. To correct the problem, use the command form:

nohup (command1; command2) 

Be careful of where standard error is redirected. The following command may put error messages on tape, making it unreadable:

nohup cpio -o <list >/dev/rmt/c0t0d0BEST& 

whereas

nohup cpio -o <list >/dev/rmt/c0t0d0BEST 2>errors& 

puts the error messages into file errors.

EXIT STATUS

The following exit values are returned:

126: The command specified by command was found but could not be invoked
127: An error occurred in the nohup utility or the specified command could not be found

Otherwise, the exit status of nohup will be that of the command specified.

STANDARDS CONFORMANCE

nohup: SVID2, SVID3, XPG2, XPG3, XPG4, POSIX.2