发现一个有用的命令pidof

这个linux命令找到某个名字的进程的pid值。如果找不到，则返回空值。

PIDOF(8) Linux System Administrator's Manual PIDOF(8)

NAME
pidof -- find the process ID of a running program.

SYNOPSIS
pidof [-s] [-c] [-x] [-o omitpid] [-o omitpid..] program [program..]

DESCRIPTION
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 System-V like rc structure. In
that case these scripts are located in /etc/rc?.d, where ? is the runlevel. If
the system has a start-stop-daemon (8) program that should be used instead.

OPTIONS
-s Single shot - this instructs the program to only return one pid.

-c Only return process ids 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.

-x Scripts too - this causes the program to also return process id's of
shells running the named scripts.

-o omitpid
Tells pidof to omit processes with that process id. The special pid
%PPID can be used to name the parent process of the pidof program, in
other words the calling shell or shell script.

EXIT STATUS
0 At least one program was found with the requested name.

1 No program was found with the requested name.

NOTES
pidof is actually the same program as killall5; the program behaves according
to the name under which it is called.

When pidof 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.

SEE ALSO
shutdown(8), init(8), halt(8), reboot(8), killall5(8)

AUTHOR
Miquel van Smoorenburg, miquels@cistron.nl

01 Sep 1998 PIDOF(8)