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dw8547
Asked: 2018-02-15 01:53:19 +0800 CST

What does the "<>" mean in "kill -9 <>"?

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I am going through a tutorial on recovering from a database failure and in the tutorial, a failure on the host of the primary database is simulated with:

kill -9 <>

I know that the kill command is used to send a signal to a process, and that 9 represents the SIGKILL signal that terminates a process, but what does the <> argument stand for?

I have read the manual pages for the kill command but still cannot figure out why and what for <> is used.

command-line kill

3 Answers

  1. Best Answer

    You're supposed to replace the <> by the process id. To get the process id, you can use the command

    ps -aux

    It will list all the processes, and you just have to choose the right process

    If you have a single instance of a process, you can also use the pkill commmand with the name of the process, eg

    pkill -9 mysql
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  2. It is 

    <pid> [...]
      Send signal to every <pid> listed.

    in manpage. There is always description inside of the <> quotes.

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  3. <> in the man page means replace <> with PID.

    In addition to the answer by Felicien using the ps command, you can also use top or htop

    top -d 10

    Use -d <> (duration) to update every <> seconds.

    To kill the process, simply note the PID and kill the process ID with:

    kill -9 xxxx

    Note: for htop, you will need to type htop -d 100 ie; 10 seconds.

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