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This article is to share with you about process management under linux-what are ps,pstree and other commands. The editor thought it was very practical, so I shared it with you as a reference. Let's follow the editor and have a look.

Process, as the name implies, running program, process as the basic operating unit of the operating system, each process has a unique process number ID, and we manage the process through this ID.

Ps

How to see the running status of each program, use the ps command. Here we talk about the concept of parent process and child process, the child process is derived from the parent process, and the process without the parent process is called the orphan process.

View the progress of the current bash environment:

# ps-lF S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD4 S 0 43530 43528 0 800-28886 do_wai pts/0 00:00:00 bash0 R 0 43552 43530 0 800-38336-pts/0 00:00:00 ps

Here UID represents the user ID,PID indicates that the process ID,PPID represents the ID of the parent process.

View all processes

# ps aux USER PID% CPU% MEM VSZ RSS TTY STAT START TIME COMMAND Root 2 0.0 0.0 0 0? S Sep29 0:00 [kthreadd] root 3 0.0 0.0 00? S Sep29 0:02 [ksoftirqd/0] root 5 0.0 0.0 0 0? S < Sep29 0:00 [kworker/0:0H].

You can view all processes through ps aux, but it does not list the parent process ID. We can use ps-lA or ps-ef to view all processes and display the parent process ID.

[root@localhost] # ps-lAF S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD4 S 0 1000 800-47844 ep_pol? 00:00:04 systemd1 S 02 00 800-0 kthrea? 00:00:00 kthreadd1 S 0 3 20 800-0 smpboo? 00:00:02 ksoftirqd/0

Pstree

Although the parent process ID is listed in all the processes above, the relationship between the parent and child processes is not clear at a glance. We can pstree to list all processes in the form of a process tree.

# pstree-upsystemd (1) ─┬─ BT-Panel (5462) ─── {BT-Panel} (5469) ├─ BT-Task (5361) ─┬─ {BT-Task} (5375) │ ├─ {BT-Task} (5376) │ ├─ (5377) │ ├─ { BT-Task} (5381) │ ├─ {BT-Task} (5382) │ └─ {BT-Task} (5390).

You can also view the number of processes for a particular process.

# pstree-p 5389-upmysqld (5389 MySQL) ─┬─ {mysqld} (5414) ├─ {mysqld} (5415) ├─ {mysqld} (5416)

Pidof

View the process ID number by the process name. For example, if I want to know the mysqld process ID, I can check it through the pidof command.

# pidof mysqld5389

Note that there may be more than one process name on the server, so pidof will find more than one process ID.

# pidof php-fpm42609 41610 41588.

Kill 、 killall

For process management, we manage the process through the process number PID and a signal signal.

The code name content 1SIGHUP starts the terminated program and allows the PID to re-read its own configuration file, similar to restarting 2SIGINT is equivalent to interrupting the progress of a program by typing [ctrl]-c on the keyboard. 9SIGKILL represents a forced interruption of the progress of a program to terminate the program with a normal termination program. Since it is a normal termination, the follow-up action will complete him. The signal is also the default value, and when no signal is added, the value is used. 19SIGSTOP is equivalent to pausing a program by typing [ctrl]-z on the keyboard.

The difference between kill and killall is that kill manages processes through process ID, while killall manages processes by process name.

# kill-15 426 destroy killall-9 php-fpm # Note, this will kill all php-fpm processes. Thank you for reading! On the process management under linux-ps,pstree and other commands are shared here, I hope the above content can be of some help to you, so that you can learn more knowledge. If you think the article is good, you can share it and let more people see it.

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