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Full Discussion: nohup.out
Operating Systems AIX nohup.out Post 302141871 by bakunin on Tuesday 23rd of October 2007 05:52:52 AM
Old 10-23-2007
Yes, there is: put a cron-job in effect, which truncates the file (by something like "cat /dev/null > nohup.out"). How often you will have to run this job depends on how much output your process generates.

But if you do not need the output of the job altogether (maybe its garbage anyways, only you can answer that) you could prevent writig to file nohup.out in first place. Right now you start the process in a way like this:

nohup command &

replace this by

nohup command 2>/dev/null 1>/dev/null &

and the file nohup.out won't even get created.

The reason why the output of the process is being directed to a file is:

Normally all processes (that is: commands you enter from commandline, there are exceptions, but they don't matter here) are attached to a terminal. Per default (this is how Unix is handling this) this is something which can display text and is connect to the host via a serial line. If you enter a command and switch off the terminal you entered it from the process gets terminated too - because it lost its terminal. Because in serial communication the technicians traditionally employed the words from telephone communication (where it came from) the termination of a communication was not called an "interruption" or "termination" but a "hangup". So programs got terminated on "hangups" and to program to prevent this was "nohup", the "no-termination-upon-hangup"-program.

But as it may well be that such an orphaned process has no terminal to write to it nohup uses the file nohup.out as a "screen-replacement", redirecting the output there, which would normally go to the screen. If a command has no output whatsoever though nohp.out won't get created.

bakunin
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LEARN ABOUT LINUX

nohup

NOHUP(1)							   User Commands							  NOHUP(1)

NAME

       nohup - run a command immune to hangups, with output to a non-tty

SYNOPSIS

       nohup COMMAND [ARG]...
       nohup OPTION

DESCRIPTION

       Run COMMAND, ignoring hangup signals.

       --help display this help and exit

       --version
	      output version information and exit

       If  standard  input is a terminal, redirect it from /dev/null.  If standard output is a terminal, append output to `nohup.out' if possible,
       `$HOME/nohup.out' otherwise.  If standard error is a terminal, redirect it to standard output.  To save output to FILE, use `nohup  COMMAND
       > FILE'.

       NOTE: your shell may have its own version of nohup, which usually supersedes the version described here.  Please refer to your shell's doc-
       umentation for details about the options it supports.

AUTHOR

       Written by Jim Meyering.

REPORTING BUGS

       Report nohup bugs to bug-coreutils@gnu.org
       GNU coreutils home page: <http://www.gnu.org/software/coreutils/>
       General help using GNU software: <http://www.gnu.org/gethelp/>
       Report nohup translation bugs to <http://translationproject.org/team/>

COPYRIGHT

       Copyright (C) 2010 Free Software Foundation, Inc.  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
       This is free software: you are free to change and redistribute it.  There is NO WARRANTY, to the extent permitted by law.

SEE ALSO

       The full documentation for nohup is maintained as a Texinfo manual.  If the info and nohup programs are properly installed  at  your  site,
       the command

	      info coreutils 'nohup invocation'

       should give you access to the complete manual.

GNU coreutils 8.5						   February 2011							  NOHUP(1)
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