Question

When looking at various daemon scripts in /etc/init.d/, I can’t seem to understand the purpose of the ‘lockfile’ variable. It seems like the ‘lockfile’ variable is not being checked before starting the daemon.

For example, some code from /etc/init.d/ntpd:

prog=ntpd
lockfile=/var/lock/subsys/$prog

start() {
        [ "$EUID" != "0" ] && exit 4
        [ "$NETWORKING" = "no" ] && exit 1
        [ -x /usr/sbin/ntpd ] || exit 5
        [ -f /etc/sysconfig/ntpd ] || exit 6
        . /etc/sysconfig/ntpd

        # Start daemons.
        echo -n $"Starting $prog: "
        daemon $prog $OPTIONS
        RETVAL=$?
        echo
        [ $RETVAL -eq 0 ] && touch $lockfile
        return $RETVAL
}

What is the ‘lockfile’ variable doing?

Also, when writing my own daemon in C++ (such as following the example at the bottom of http://www.itp.uzh.ch/~dpotter/howto/daemonize), do I put the compiled binary directly in /etc/init.d/ or do I put a script there that calls the binary. (i.e. replacing the ‘daemon $prog’ in the code above with a call to my binary?)

Answer 1

What is the ‘lockfile’ variable doing?

It could be nothing or it could be eg. injected into $OPTIONS by this line

   . /etc/sysconfig/ntpd

The daemon takes the option -p pidfile where $lockfile could go. The daemon writes its $PID in this file.

do I put the compiled binary directly in /etc/init.d/ or do I put a script there that calls the binary

The latter. There should be no binaries in /etc, and its customary to edit /etc/init.d scripts for configuration changes. Binaries should go to /(s)bin or /usr/(s)bin.