This tutorial explains Linux “kill” command, options and its usage with examples.
DESCRIPTION
Even on Linux it sometimes happens that processes wear out their welcome and stick around longer than you would like them to. They simply ignore your request to close up and go away. Fortunately you have a powerful gun at your disposal that will clean out anything that doesn’t get a hint: The Arnold Schwarzenegger equivalent among the Linux commands is the kill command.
There are many different signals that can be sent , although the signals in which users are generally most interested are SIGTERM and SIGKILL. The default signal sent is SIGTERM. Programs that handle this signal can do useful cleanup operations (such as saving configuration information to a file) before quitting. However, many programs do not implement a special handler for this signal, and so a default signal handler is called instead. Other times, even a process that has a special handler has gone awry in a way that prevents it from properly handling the signal.
SYNOPSIS
kill [options] OPTIONS Common UNIX Signal Names and Numbers Alternate signals may be specified in three ways: -9,-SIGKILL or -KILL. Negative PID values may be used to choose whole process groups; see the PGID column in ps command output. A PID of -1 is special; it indicates all processes except the kill process itself and init. EXAMPLES 1. Send a Kill Single To Process ID 1414 To find pid of any job or command use ps command: 2. Forcefully kill 1414 process OR OR OR OR 3. To stop all of your processes and log yourself off, enter the following command This sends signal 9, the SIGKILL signal, to all processes that have a process group ID equal to the senders process group ID. Because the shell cannot ignore the SIGKILL signal, this command also stops the login shell and logs you off. 4. To stop all processes that you own, enter the following command This sends signal 9, the SIGKILL signal, to all processes owned by the effective user 5. Display ginal names
Send signal to every
–
Specify the signal to be sent. The signal can be specified by using name or number.
-l, –list [signal]
List signal names. This option has optional argument, which will convert signal number to signal name, or other way round.
-L, –table
List signal names in a nice table.
Number
Name
Description
Used for
0
SIGNULL
Null
Check access to pid
1
SIGHUP
Hangup
Terminate; can be trapped
2
SIGINT
Interrupt
Terminate; can be trapped
3
SIGQUIT
Quit
Terminate with core dump; can be
9
SIGKILL
Kill
Forced termination; cannot be trapped
15
SIGTERM
Terminate
Terminate; can be trapped
24
SIGSTOP
Stop
Pause the process; cannot be trapped
25
SIGTSTP
Terminal
stop Pause the process; can be
26
SIGCONT
Continue
Run a stopped process
$ kill 4242
$ ps | grep command
$ ps aux | grep command
$ ps aux | grep apache
$ kill -s SIGKILL 1414
$ kill -s KILL 1414
$ kill -s 9 1414
$ kill -SIGKILL 1414
$ kill -KILL 1414
$ kill -kill 0
$ kill -9 -1
# kill -L
1 HUP 2 INT 3 QUIT 4 ILL 5 TRAP 6 ABRT 7 BUS
8 FPE 9 KILL 10 USR1 11 SEGV 12 USR2 13 PIPE 14 ALRM
15 TERM 16 STKFLT 17 CHLD 18 CONT 19 STOP 20 TSTP 21 TTIN
22 TTOU 23 URG 24 XCPU 25 XFSZ 26 VTALRM 27 PROF 28 WINCH
29 POLL 30 PWR 31 SYS
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