Re: "Boot time scripts should have an .sh extension"

From: Joep Vesseur (Joep.Vesseur_at_Sun.COM)
Date: 11/14/03

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    To: Paul Greene <techlists@comcast.net>
Date: Fri, 14 Nov 2003 16:02:05 +0100

    Paul,

    > The umask has .sh (/etc/init.d/umask.sh)
    >
    > Note: The trailing .sh is very important because boot time scripts which
    > do not end in .sh get executed in a child shell rather in the
    > environment of the parent init process. The parent will not inherit the
    > umask value from a child shell, so the new umask value would be lost.

    It is sort of true, but not completely. init(1M) will fork of a shell
    that runs /sbin/rc<L> where <L> is the runlevel. So, to start with the
    false part: none of the subsequent scripts "run in the environment of
    the parent init process".

    Then the correct part: each of the /sbin/rc* files will "source" an
    init file that ends with ".sh", and will start a new shell for other
    files, e.g. see /sbin/rc2:

      [...]
                      if [ -s $f ]; then
                            case $f in
                                    *.sh) . $f ;;
                                    *) /sbin/sh $f start ;;
                            esac
      [...]

    So you can alter the environment of, in this case, /sbin/rc2 and thus of
    all scripts subsequently run by rc2, but you can't alter the environment
    of init(1M) itself.

    Hope this helps,

    Joep

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