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APUEの中に書いてあるdaemonの書き方

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Daemon Coding Rules


  1. call umask to set file mode creation mask.


  2. fork and have parent process exit.


    • When invoked as shell command, letting parent exit make the shell think the command is finished

    • ensure that the child process is not a process group leader. This is a prerequisite for setsid



  3. call setsid


    • The child process will be the leader of the new process group

    • The child process will be the leader of the new process session

    • The child process will be detached from its controlling terminal



  4. chdir

  5. close files inherited from its parent

  6. redirect stdin, stdout, stderr to /dev/null