ThePIDOF.andpgrepcommands provide listings of process IDs (PIDs) for process names that you provide as arguments. This post shows how to use these commands and illustrates the differences between them with a series of examples.
PIDOF.
There are a number of ways to determine the PID of a process running on a Linux system, but the easiest is probably a command calledPIDOF.。Read this as “PID of” and you’ll have an easy time remembering it. Using this command, you can get the PID of a process by typing “pidof” and specifying the process name. For example:
$ pidof bash 1262005
If you were to run thepscommand without arguments, you will get a list of the processes that you’re running in your current shell. The command below shows where the response above comes from:
$ ps PID TTY TIME CMD1262005pts/0 00:00:00 bash
If more than one person is logged in and using抨击, the response to that command will includeall对于BASH进程的关联PID，您不一定知道没有一些PID属于Shell的其他命令：
pidof bash 1265446 1262005美元
You could run a command like this to show just your shell:
$ ps | grep bash | awk ‘{print $1}’
1262005
To get a listing of PIDs for system processes likesystemd, you could run a command like this one:
$ pidof systemd 1265265 1261815 1548 1
Notice that the output shows that foursystemdprocesses are running. To display just one PID, you can add the-soption, but thePIDOF.command will only then be providing the largest (more recently started) PID in the group.
$ pidof -s systemd 1265265
If you get no response when you usePIDOF., the process you are asking about either isn’t running or you mistyped its name.
$ pidof apache2 $
Interestingly, if you do a file listing forPIDOF., you’ll see that it’s nothing more than a symbolic link to another program,killall5on this system.
$ which pidof /bin/pidof $ ls -l /bin/pidof lrwxrwxrwx 1 root root 14 Feb 13 2020 /bin/pidof -> /sbin/killall5
Even so, the executable behaves very differently when it’s calledPIDOF.。When invoked withkillall5, the command is one of a number of commands that is used to terminate processes. When referred to asPIDOF., it returns PIDs.
pgrep
Thepgrepcommand works a lot likePIDOF., but there are some differences both in the content and the arrangement of its output. For example, when we usePIDOF.to get a list of PIDs forsystemd, we get a list like this one:
$ pidof systemd 1261815 1548 1
When we usepgrep另一方面，我们获得PID的垂直列表，并查看更多条目。为什么？因为pgrep行为更像grep。它寻找包含作为参数提供的字符串的进程，而不仅仅是那些符合进程名称的字符串。
$ pgrep systemd 1 1010 1548 171864 171907 172061 1261815
In the command below, you can see more details on the processes that the above command selected:
$ ps -eo pid,euser,comm | grep systemd 1 root systemd 1010 root systemd-logind 1548 gdm systemd 171864 systemd+ systemd-resolve 171907 root systemd-journal 172061 root systemd-udevd 1261815 shs system
Wrap-Up
Selecting process IDs can be very useful at times, and thePIDOF.andpgrepcommands keep you from having to pipe the output of commands to other commands to narrow down the output to a list containing only process IDs.
Now see: