path: root/usr/src/man/man1/nohup.1

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.TH NOHUP 1 "Jun 19, 2006"
.SH NAME
nohup \- run a command immune to hangups
.SH SYNOPSIS
.LP
.nf
\fB/usr/bin/nohup\fR \fIcommand\fR [\fIargument\fR]...
.fi

.LP
.nf
\fB/usr/bin/nohup\fR \fB-p\fR [\fB-Fa\fR] \fIpid\fR [\fIpid\fR]...
.fi

.LP
.nf
\fB/usr/bin/nohup\fR \fB-g\fR [\fB-Fa\fR] \fIgpid\fR [\fIgpid\fR]...
.fi

.LP
.nf
\fB/usr/xpg4/bin/nohup\fR \fIcommand\fR [\fIargument\fR]...
.fi

.SH DESCRIPTION
.sp
.LP
The \fBnohup\fR utility invokes the named \fIcommand\fR with the arguments
supplied.  When the \fIcommand\fR is invoked, \fBnohup\fR arranges for the
\fBSIGHUP\fR signal to be ignored by the process.
.sp
.LP
When invoked with the \fB-p\fR or \fB-g\fR flags, \fBnohup\fR arranges for
processes already running as identified by a list of process \fBID\fRs or a
list of process group \fBID\fRs to become immune to hangups.
.sp
.LP
The \fBnohup\fR utility can be used when it is known that \fIcommand\fR takes a
long time to run and the user wants to log out of the terminal. When a shell
exits, the system sends its children \fBSIGHUP\fR signals, which by default
cause them to be killed. All stopped, running, and background jobs ignores
\fBSIGHUP\fR and continue running, if their invocation is preceded by the
\fBnohup\fR command or if the process programmatically has chosen to ignore
\fBSIGHUP\fR.
.sp
.ne 2
.na
\fB\fB/usr/bin/nohup\fR\fR
.ad
.RS 27n
Processes run by \fB/usr/bin/nohup\fR are immune to \fBSIGHUP\fR (hangup) and
\fBSIGQUIT\fR (quit) signals.
.RE

.sp
.ne 2
.na
\fB\fB/usr/bin/nohup\fR \fB-p\fR [\fB-Fa\fR]\fR
.ad
.RS 27n
Processes specified by \fBID\fR are made immune to \fBSIGHUP\fR and
\fBSIGQUIT\fR, and all output to the controlling terminal is redirected to
\fBnohup.out\fR. If \fB-F\fR is specified, \fBnohup\fR forces control of each
process. If \fB-a\fR is specified, \fBnohup\fR changes the signal disposition
of \fBSIGHUP\fR and \fBSIGQUIT\fR even if the process has installed a handler
for either signal.
.RE

.sp
.ne 2
.na
\fB\fB/usr/bin/nohup\fR \fB-g\fR [\fB-Fa\fR]\fR
.ad
.RS 27n
Every process in the same process group as the processes specified by \fBID\fR
are made immune to \fBSIGHUP\fR and \fBSIGQUIT\fR, and all output to the
controlling terminal is redirected to \fBnohup.out\fR. If \fB-F\fR is
specified, \fBnohup\fR forces control of each process. If \fB-a\fR is
specified, \fBnohup\fR changes the signal disposition of \fBSIGHUP\fR and
\fBSIGQUIT\fR even if the process has installed a handler for either signal.
.RE

.sp
.ne 2
.na
\fB\fB/usr/xpg4/bin/nohup\fR\fR
.ad
.RS 27n
Processes run by \fB/usr/xpg4/bin/nohup\fR are immune to \fBSIGHUP\fR.
.sp
The \fBnohup\fR utility does not arrange to make processes immune to a
\fBSIGTERM\fR (terminate) signal, so unless they arrange to be immune to
\fBSIGTERM\fR or the shell makes them immune to \fBSIGTERM\fR, they will
receive it.
.sp
If \fBnohup.out\fR is not writable in the current directory, output is
redirected to \fB$HOME/nohup.out\fR. If a file is created, the file has read
and write permission (\fB600\fR. See \fBchmod\fR(1). 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 \fBnohup\fR is not altered.
.RE

.SH OPTIONS
.sp
.LP
The following options are supported:
.sp
.ne 2
.na
\fB\fB-a\fR\fR
.ad
.RS 6n
Always changes the signal disposition of target processes. This option is valid
only when specified with \fB-p\fR or \fB-g\fR.
.RE

.sp
.ne 2
.na
\fB\fB-F\fR\fR
.ad
.RS 6n
Force. Grabs the target processes even if another process has control. This
option is valid only when specified with \fB-p\fR or \fB-g.\fR
.RE

.sp
.ne 2
.na
\fB\fB-g\fR\fR
.ad
.RS 6n
Operates on a list of process groups. This option is not valid with \fB-p\fR.
.RE

.sp
.ne 2
.na
\fB\fB-p\fR\fR
.ad
.RS 6n
Operates on a list of processes. This option is not valid with \fB-g\fR.
.RE

.SH OPERANDS
.sp
.LP
The following operands are supported:
.sp
.ne 2
.na
\fB\fIpid\fR\fR
.ad
.RS 12n
A decimal process \fBID\fR to be manipulated by \fBnohup\fR \fB-p\fR.
.RE

.sp
.ne 2
.na
\fB\fIpgid\fR\fR
.ad
.RS 12n
A decimal process group \fBID\fR to be manipulated by \fBnohup\fR \fB-g\fR.
.RE

.sp
.ne 2
.na
\fB\fIcommand\fR\fR
.ad
.RS 12n
The name of a command that is to be invoked. If the \fIcommand\fR operand names
any of the special \fBshell_builtins\fR(1) utilities, the results are
undefined.
.RE

.sp
.ne 2
.na
\fB\fIargument\fR\fR
.ad
.RS 12n
Any string to be supplied as an argument when invoking the \fIcommand\fR
operand.
.RE

.SH USAGE
.sp
.LP
Caution should be exercised when using the \fB-F\fR flag. Imposing two
controlling processes on one victim process can lead to chaos. Safety is
assured only if the primary controlling process, typically a debugger, has
stopped the victim process and the primary controlling process is doing nothing
at the moment of application of the \fBproc\fR tool in question.
.SH EXAMPLES
.LP
\fBExample 1 \fRApplying nohup to pipelines or command lists
.sp
.LP
It is frequently desirable to apply \fBnohup\fR 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. One can then issue:

.sp
.in +2
.nf
example$ \fBnohup sh \fIfile\fR\fR	
.fi
.in -2
.sp

.sp
.LP
and the \fBnohup\fR applies to everything in \fIfile\fR. If the shell script
\fIfile\fR is to be executed often, then the need to type \fBsh\fR can be
eliminated by giving \fIfile\fR execute permission.

.sp
.LP
Add an ampersand and the contents of \fIfile\fR are run in the background with
interrupts also ignored (see \fBsh\fR(1)):

.sp
.in +2
.nf
example$ \fBnohup \fIfile\fR &\fR
.fi
.in -2
.sp

.LP
\fBExample 2 \fRApplying nohup -p to a process
.sp
.in +2
.nf
example$ \fBlong_running_command &\fR
example$ \fBnohup -p `pgrep long_running_command`\fR
.fi
.in -2
.sp

.LP
\fBExample 3 \fRApplying nohup -g to a process group
.sp
.in +2
.nf
example$ \fBmake &\fR
example$ \fBps -o sid -p $$\fR
   SID
81079
example$ \fBnohup -g `pgrep -s 81079 make`\fR
.fi
.in -2
.sp

.SH ENVIRONMENT VARIABLES
.sp
.LP
See \fBenviron\fR(7) for descriptions of the following environment variables
that affect the execution of \fBnohup\fR: \fBLANG\fR, \fBLC_ALL\fR,
\fBLC_CTYPE\fR, \fBLC_MESSAGES\fR, \fBPATH\fR, \fBNLSPATH\fR, and \fBPATH\fR.
.sp
.ne 2
.na
\fB\fBHOME\fR\fR
.ad
.RS 8n
Determine the path name of the user's home directory: if the output file
\fBnohup.out\fR cannot be created in the current directory, the \fBnohup\fR
command uses the directory named by \fBHOME\fR to create the file.
.RE

.SH EXIT STATUS
.sp
.LP
The following exit values are returned:
.sp
.ne 2
.na
\fB\fB126\fR\fR
.ad
.RS 7n
\fIcommand\fR was found but could not be invoked.
.RE

.sp
.ne 2
.na
\fB\fB127\fR\fR
.ad
.RS 7n
An error occurred in \fBnohup\fR, or \fIcommand\fR could not be found
.RE

.sp
.LP
Otherwise, the exit values of \fBnohup\fR are those of the \fIcommand\fR
operand.
.SH FILES
.sp
.ne 2
.na
\fB\fBnohup.out\fR\fR
.ad
.RS 19n
The output file of the \fBnohup\fR execution if standard output is a terminal
and if the current directory is writable.
.RE

.sp
.ne 2
.na
\fB\fB$HOME/nohup.out\fR\fR
.ad
.RS 19n
The output file of the \fBnohup\fR execution if standard output is a terminal
and if the current directory is not writable.
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.SS "/usr/bin/nohup"
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
CSI	Enabled
.TE

.SS "/usr/xpg4/bin/nohup"
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
CSI	Enabled
_
Interface Stability	Standard
.TE

.SH SEE ALSO
.sp
.LP
.BR batch (1),
.BR chmod (1),
.BR csh (1),
.BR ksh (1),
.BR nice (1),
.BR pgrep (1),
.BR proc (1),
.BR ps (1),
.BR sh (1),
.BR shell_builtins (1),
.BR signal (3C),
.BR proc (5),
.BR attributes (7),
.BR environ (7),
.BR standards (7)
.SH WARNINGS
.sp
.LP
If you are running the Korn shell (\fBksh\fR(1)) as your login shell, and have
\fBnohup\fR'ed jobs running when you attempt to log out, you are warned with
the message:
.sp
.in +2
.nf
You have jobs running.
.fi
.in -2
.sp

.sp
.LP
You need to log out a second time to actually log out. However, your background
jobs continues to run.
.SH NOTES
.sp
.LP
The C-shell (\fBcsh\fR(1)) has a built-in command \fBnohup\fR that provides
immunity from \fBSIGHUP\fR, but does not redirect output to \fBnohup.out\fR.
Commands executed with `\fB&\fR\&' are automatically immune to \fBHUP\fR
signals while in the background.
.sp
.LP
\fBnohup\fR does not recognize command sequences. In the case of the following
command,
.sp
.in +2
.nf
example$ \fBnohup command1; command2\fR
.fi
.in -2
.sp

.sp
.LP
the \fBnohup\fR utility applies only to \fBcommand1\fR. The command,
.sp
.in +2
.nf
example$ \fBnohup (command1; command2)\fR
.fi
.in -2
.sp

.sp
.LP
is syntactically incorrect.