6 ms·

kill = send a signal. By far the easiest question to weed out inexperienced linux users.

• ababab 13y ago
  Shouldn't that explanation be by followed by 'in order to request the termination of the process'?
  • beedogs 13y ago
    Not necessarily. You can send the CONTinue signal to a process using the kill command. This will not cause the process to terminate.
    • twinge 13y ago
      Or use "kill -0 <pid>" to check if a signal can be sent/the pid exists.
      • rahimnathwani 13y ago
        Or use kill -USR1 <pid> to check the progress of dd
        • DHowett 13y ago
          Only if you've enabled it. If you've not, the process will terminate unceremoniously (in a mechanism borne entirely out of hatred for users.) This is my favourite part of dd: The "will I receive a status report or will I terminate my long-running copy?" gamble.
          • jsight 13y ago
            Is that a BSD thing? I've never had to enable it on Linux to avoid killing the process.
            • rahimnathwani 13y ago
              Me neither, on debian.
        • Freaky 13y ago
          It's SIGINFO on the BSD's, and works with just about any process (though obviously not everything has a customized handler). Also handily mapped to Ctrl-T.
  • habosa 13y ago
    Not always. The kill system call can be used to send any signal, it's just got a name that implies you're sending something like SIGKILL or SIGTERM. I have written C programs that use kill for harmless inter-process communication.
    • eru 13y ago
      SIGUSER is quite common for that. Or SIGHUP.
      • brokenparser 13y ago
        By convention, SIGHUP is used by daemons to signal a change of configuration.
  • nailer 13y ago
    You can also cancel (sigint, eg ctrl c) processes via kill. Or use sigchld to a parent to get rid of zombie children.
  • brokenparser 13y ago
    No because only SIGQUIT, SIGABRT, SIGKILL, SIGTERM and often SIGHUP are supposed to do that. All of the other signals have wildly varying meanings. See man 7 signal: http://unixhelp.ed.ac.uk/CGI/man-cgi?signal+7 http://unixhelp.ed.ac.uk/CGI/man-cgi?signal+7
  • drivers99 13y ago
    SIGHUP is also used to tell some certain daemons to re-read their configuration files without quitting.