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157 lines
6.4 KiB
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What Options you use for Linux killall Command ? I have 5 Options
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Linux command line offers various commands to kill a process. For example, the ‘kill’ command can be used to kill a process by passing its PID as an argument, the ‘pkill’ command takes a pattern as an input and all the matching running processes are killed. But there exists a command ‘killall’, which exactly matches the argument name by default, and kills the matching process. In this article, we will discuss this command with some practical examples.
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### Linux killall Command ###
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The killall command can be used to send a signal to a particular process. The signal can be specified as an argument to this command or else SIGTERM is sent by default.
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Lets discuss the usage of this command through some practical examples.
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#### 1. A basic example ####
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In this example, we will show how killall command can be used to kill a particular process. Suppose, there are two processes that have same initial characters :
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$ ps -aef | grep “test”
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himanshu 3969 2811 0 14:14 pts/0 00:00:00 ./test
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himanshu 3970 2811 0 14:14 pts/0 00:00:00 ./test_again
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Now, here is how you can use the killall command to kill ‘test_again’ :
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$ killall test_again
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[2]+ Terminated ./test_again
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As you can see, the ‘killall’ command terminated the ‘test_again’ process. This can also be confirmed through the ps command :
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$ ps -aef | grep “test”
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himanshu 3969 2811 0 14:14 pts/0 00:00:00 ./test
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Observe that ‘test_again’ is not displayed in the output as it is killed.
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#### 2. Ignore case using -I option ####
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The killall command is case-sensitive by default. Here is an example :
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$ ps -aef | grep “test”
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himanshu 4177 3161 0 14:54 pts/3 00:00:00 ./test
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himanshu 4178 3161 0 14:54 pts/3 00:00:00 ./test_again
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himanshu 4180 3161 0 14:54 pts/3 00:00:00 grep --color=auto test
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$ killall TEST
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TEST: no process found
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So you can see that the killall command could not find any process named TEST, while a process named ‘test’ is already running.
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To make sure that the killall command ignores the case, use the -I option. Here is an example :
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$ killall -I TEST
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[1]- Terminated ./test
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Observe that now it successfully terminated the ‘test’ process.
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#### 3. Kill processes interactively using -i option ####
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The killall command can be used to kill more than process.
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$ killall test test_again
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[2]- Terminated ./test_again
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[3]+ Terminated ./test
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But, if you want killall to terminate processes interactively, you can use the -i option.
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Here is an example :
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$ killall -i test test_again
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Kill test(4201) ? (y/N) y
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Kill test_again(4202) ? (y/N) y
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[1]- Terminated ./test
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[2]+ Terminated ./test_again
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So you can see that this way user can control the termination of processes using killall command.
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#### 4. Disable details if no processes were killed using -q option ####
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Sometimes when killall is not able to find a specified process, it complains about the same in the output.
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Here is an example :
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$ killall TEST
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TEST: no process found
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But, in case you want killall to carry out its work quietly, you can use the -q option :
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$ killall -q TEST
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$
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So you can see that when -q was used, the output was suppressed.
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#### 5. List all the supported signals in output using -l option ####
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As already described in the beginning, killall sends signals to processes. You can use the -s option (followed by the signal name) to send a particular signal to a process.
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To know, what all signals this command can send, use the -l option.
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$ killall -l
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HUP INT QUIT ILL TRAP ABRT IOT BUS FPE KILL USR1 SEGV USR2 PIPE ALRM TERM
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STKFLT CHLD CONT STOP TSTP TTIN TTOU URG XCPU XFSZ VTALRM PROF WINCH IO PWR SYS
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UNUSED
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So killall supports all these signals.
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### Something to discuss ###
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The man page of the killall command says that by default, it matches complete names only if they are less than or equal to 15 characters in length.
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For example, suppose there are following two processes with long names :
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$ ps -aef | grep “test”
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himanshu 4021 3161 0 14:27 pts/3 00:00:00 ./test_abcdefghij
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himanshu 4035 3161 0 14:27 pts/3 00:00:00 ./test_abcdefgh
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The first process in the output above has exactly 15 characters in name. Lets try to kill it using the killall command :
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$ killall test_abcdefghij
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[1]- Terminated ./test_abcdefghij
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So you can see that the killall command kills the process successfully.
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Now, according to the man page, if both the names would have had more than 15 matching characters, killall would have killed both the processes. Here is an example :
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$ ps -aef | grep “test”
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himanshu 4114 3161 0 14:40 pts/3 00:00:00 ./test_abcdefghijklmnopqrstuvwx
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himanshu 4141 3161 0 14:46 pts/3 00:00:00 ./test_abcdefghijklmnopqrstuvwxyz
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himanshu 4143 3161 0 14:46 pts/3 00:00:00 grep --color=auto test
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Observe that both the processes now have more than 15 matching characters in their name. Now, when I tried to kill the second process using killall :
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$ killall test_abcdefghijklmnopqrstuvwxyz
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[6]+ Terminated ./test_abcdefghijklmnopqrstuvwxyz
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It killed only the specified process, and not the other one.
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$ ps -aef | grep “test”
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himanshu 4114 3161 0 14:40 pts/3 00:00:00 ./test_abcdefghijklmnopqrstuvwx
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himanshu 4146 3161 0 14:47 pts/3 00:00:00 grep --color=auto test
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I am not sure if there is something incorrect on my side, or it is a bug in killall command. I’d appreciate if you put forward your views on this in comments.
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BTW, here are the details of killall command on my system :
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$ killall --version
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killall (PSmisc) 22.20
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Copyright (C) 1993-2012 Werner Almesberger and Craig Small
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PSmisc comes with ABSOLUTELY NO WARRANTY.
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This is free software, and you are welcome to redistribute it under
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the terms of the GNU General Public License.
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For more information about these matters, see the files named COPYING.
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--------------------------------------------------------------------------------
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via: http://linoxide.com/linux-command/linux-killall-my-options/
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译者：[译者ID](https://github.com/译者ID) 校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出 |