Linux terminates the process command: kill

a kill command

1. kill -9 process number

Force the process to stop immediately

[root@localhost ~]# kill -9 22
[root@localhost ~]# 

2. kill -15 process ID

graceful shutdown process

3.kill -h

Find all process serial numbers

Two pkill command

The disadvantage of the kill method is that when we have many processes to kill, it is impossible to manually enter the process numbers one by one. pkill can kill processes according to the keywords in the process name, so that we can kill them in batches

• kill everything with the python keyword

pkill -9 python

• pkill -h

[root@localhost ~]# pkill -h

Usage:
 pkill [options] <pattern>

Options:
 -<sig>, --signal <sig>    signal to send (either number or name)
 -e, --echo                display what is killed
 -c, --count               count of matching processes
 -f, --full                use full process name to match
 -g, --pgroup <PGID,...>   match listed process group IDs
 -G, --group <GID,...>     match real group IDs
 -n, --newest              select most recently started
 -o, --oldest              select least recently started
 -P, --parent <PPID,...>   match only child processes of the given parent
 -s, --session <SID,...>   match session IDs
 -t, --terminal <tty,...>  match by controlling terminal
 -u, --euid <ID,...>       match by effective IDs
 -U, --uid <ID,...>        match by real IDs
 -x, --exact               match exactly with the command name
 -F, --pidfile <file>      read PIDs from file
 -L, --logpidfile          fail if PID file is not locked
 --ns <PID>                match the processes that belong to the same
                           namespace as <pid>
 --nslist <ns,...>         list which namespaces will be considered for
                           the --ns option.
                           Available namespaces: ipc, mnt, net, pid, user, uts

 -h, --help     display this help and exit
 -V, --version  output version information and exit

For more details see pgrep(1).

Three process life cycle

A process is an execution process of a program. The process is introduced to realize the concurrency and real-time performance of the operating system. Generally, when you click top, you will see that this number keeps beating, indicating that the process is dynamic.

There are five main states: running state, ready state, blocking state, creation state, and end state. The
process description information is divided into two parts:

• PID: process identifier
• UID: user identifier
  Generally kill is this PID, PID is an important part of PCB, and PCB as a whole