Manual page for NOHUP(1V)
nohup - run a command immune to hangups and quits
SYNOPSIS
/usr/bin/nohup
command
[ arguments ]
SYSTEM V SYNOPSIS
/usr/5bin/nohup
command
[ arguments ]
AVAILABILITY
The System V version of this command is available with the
System V
software installation option. Refer to
[a manual with the abbreviation INSTALL]
for information on how to install optional software.
DESCRIPTION
There are three distinct versions of
nohup:
it is built in to the C shell, and is an executable program
available in
/usr/bin/nohup
and
/usr/5bin/nohup
when using the Bourne shell.
The Bourne shell version of
nohup
executes
command
such that it is immune to
HUP
(hangup)
and
TERM
(terminate)
signals.
If the standard output is a terminal, it is redirected to the file
nohup.out.
The standard error is redirected to follow the standard output.
The priority is incremented by 5.
nohup
should be invoked from the shell with
`&'
in order to
prevent it from responding to interrupts
or input from the next user.
SYSTEM V DESCRIPTON
Processes run by
nohup
are immune to
HUP
(hangup)
and
QUIT
(quit)
signals;
nohup
does not arrange to make them immune to a
TERM
(terminate) signal, so unless they arrange to be immune to a
TERM
signal, or the shell makes them immune to a
TERM
signal, they will receive that signal.
If
nohup.out
is not writable in the current directory,
output is redirected to
$HOME/nohup.out.
If the standard error is a terminal,
it is redirected to the standard output, otherwise it is not redirected.
The priority of the process run by
nohup
is not altered.
EXAMPLE
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.
The command
example% nohup sh script
applies to everything in
script.
(If the script is to be executed often,
then the need to type
sh
can be eliminated by giving
script
execute permission). Add an ampersand and the contents of
script
are run in the background with interrupts also ignored (see
sh.1
example% nohup script &
FILES
- nohup.out
-
- $HOME/nohup.out
-
SEE ALSO
chmod.1v
csh.1
nice.1
sh.1
signal.3v
BUGS
If you use
csh.1
then commands executed with
`&'
are automatically immune to
HUP
signals while in the background.
There is a C shell built-in command
nohup
that provides immunity from terminate, but does not
redirect output to
nohup.out.
nohup
does not recognize command sequences. For instance,
nohup command1; command2
applies only to
command1
and the command:
nohup (command1; command2)
is syntactically incorrect.
Be careful of where the standard error is redirected.
The following command may put error messages on tape,
making it unreadable:
nohup cpio -o < list > /dev/rmt/1m&
while
nohup cpio -o < list > /dev/rmt/1m 2>errors&
puts the error messages into the file
errors.
Created by unroff & hp-tools.
© somebody (See intro for details). All Rights Reserved.
Last modified 11/5/97
