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.\" Copyright (C) 1998 Miquel van Smoorenburg.
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.TH PIDOF 8 "01 Sep 1998" "" "Linux System Administrator's Manual"
.SH NAME
pidof -- find the process ID of a running program.
.SH SYNOPSIS
.B pidof
.RB [ \-s ]
.RB [ \-c ]
.RB [ \-n ]
.RB [ \-x ]
.RB [ \-z ]
.RB [ \-o
.IR omitpid[,omitpid...] ]
.RB [ \-o
.IR omitpid[,omitpid...]... ]
.RB [ \-d
.IR sep ]
.B program
.RB [ program... ]
.SH DESCRIPTION
.B Pidof
finds the process id's (PIDs) of the named programs. It prints those
id's on the standard output. This program is on some systems used in
run-level change scripts, especially when the system has a
\fISystem-V\fP like \fIrc\fP structure. In that case these scripts are
located in /etc/rc?.d, where ? is the runlevel. If the system has
a
.B start-stop-daemon
(8) program that should be used instead.
.SH OPTIONS
.IP \-s
Single shot - this instructs the program to only return one \fIpid\fP.
.IP \-c
Only return process PIDs that are running with the same root directory.
This option is ignored for non-root users, as they will be unable to check
the current root directory of processes they do not own.
.IP \-n
Avoid
.BR stat (2)
system function call on all binaries which are located on network
based file systems like
.BR NFS .
Instead of using this option the variable
.B PIDOF_NETFS
may be set and exported.
.IP \-q
Do not display matched PIDs to standard out. Simply exit with
a status of true or false to indicate whether a matching PID was found.
.IP \-x
Scripts too - this causes the program to also return process id's of
shells running the named scripts.
.IP \-z
Try to detect processes which are stuck in uninterruptible (D) or zombie (Z)
status. Usually these processes are skipped as trying to deal with them can cause
pidof to hang. 
.IP "-d \fIsep\fP"
Tells \fIpidof\fP to use \fIsep\fP as an output separator if more than one PID
is shown. The default separator is a space.
.IP "-o \fIomitpid\fP"
Tells \fIpidof\fP to omit processes with that process id. The special
pid \fB%PPID\fP can be used to name the parent process of the \fIpidof\fP
program, in other words the calling shell or shell script.
.SH "EXIT STATUS"
.TP
.B 0
At least one program was found with the requested name.
.TP
.B 1
No program was found with the requested name.
.SH NOTES
\fIpidof\fP is actually the same program as \fIkillall5\fP;
the program behaves according to the name under which it is called.
.PP
When \fIpidof\fP is invoked with a full pathname to the program it
should find the pid of, it is reasonably safe. Otherwise it is possible
that it returns PIDs of running programs that happen to have the same name
as the program you're after but are actually other programs. Note 
that the executable name of running processes is calculated with
.BR readlink (2),
so symbolic links to executables will also match.
.PP
Zombie processes or processes in disk sleep (states Z and D, respectively)
are ignored, as attempts to access the stats of these will sometimes fail.
The \-z flag (see above) tells pidof to try to detect these sleeping and zombie
processes, at the risk of failing or hanging.

.SH SEE ALSO
.BR shutdown (8),
.BR init (8),
.BR halt (8),
.BR reboot (8),
.BR killall5 (8)
.SH AUTHOR
Miquel van Smoorenburg, miquels@cistron.nl