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audiodef
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PostPosted: Fri Aug 16, 2013 3:17 pm    Post subject: Init script doesn't capture pid Reply with quote

I have the following init script. I need to modify it, and I'm not sure how. It is supposed to be used like net.lo - you make a symlink to it such as liquidsoap.main. The problem is, when I do that, it starts the first process and thereafter produces no error about new processes, but the new processes aren't actually started.

For example, /etc/init.d/liquidsoap.main start starts up and everything works as expected. If I then do /etc/init.d/liquidsoap.ambient start, I can see ambient.pid in /usr/local/var/run/liquidsoap, but there is no process other than liquidsoap.main found by ps aux | grep liquidsoap.

How should this script be changed to fix this?

/etc/init.d/liquidsoap:

Code:

#!/sbin/runscript

script=${RC_SVCNAME#*.}
scriptfile="/etc/liquidsoap/${script}.liq"
command=/usr/local/bin/liquidsoap
command_args="--daemon -t ${scriptfile}"
start_stop_daemon_args="--user liquidsoap:liquidsoap --nicelevel -15 "
pidfile="/usr/local/var/run/liquidsoap/${script}.pid"
name=${RC_SVCNAME}

description="Liquidsoap deamon that obeys ${scriptfile}"
extra_commands="check"
description_check="Check and evaluate stream scripts without interupting streaming."

depend() {
    need localmount
    use net
    after alsasound icecast
}

_script_exists() {
    if [ "${script}" = "${RC_SVCNAME}" ]; then
        eerror "You have to create an init script for each stream script:"
        eerror "ln -s liquidsoap /etc/init.d/liquidsoap.<script>"
        eerror "where script refers to /etc/liquidsoap/<script>.liq"
        return 1
    fi

    if [ ! -f "${scriptfile}" ]; then
        eerror "${scriptfile} not found"
        return 1
    fi
}

check() {
    _script_exists || return 1
    einfo "Checking ${scriptfile}"
    use net
    after alsasound icecast
}

_script_exists() {
    if [ "${script}" = "${RC_SVCNAME}" ]; then
        eerror "You have to create an init script for each stream script:"
        eerror "ln -s liquidsoap /etc/init.d/liquidsoap.<script>"
        eerror "where script refers to /etc/liquidsoap/<script>.liq"
        return 1
    fi

    if [ ! -f "${scriptfile}" ]; then
        eerror "${scriptfile} not found"
        return 1
    fi
}

check() {
    _script_exists || return 1
    einfo "Checking ${scriptfile}"
    check_result=`$command --check-lib ${scriptfile}`
    eend $? ${check_result}
    return $?
}

start_pre() {
    _script_exists || return 1
}

start() {
    start-stop-daemon --start  \
        ${start_stop_daemon_args} \
        --pidfile ${pidfile} \
        --exec ${command} \
        -- ${command_args}
}

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Naib
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PostPosted: Fri Aug 16, 2013 3:42 pm    Post subject: Reply with quote

sounds like it crashed.
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audiodef
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PostPosted: Fri Aug 16, 2013 3:44 pm    Post subject: Reply with quote

All I can tell you is that it runs - reliably. But stop() and restart() claim there is no such process when in fact it is running (and working correctly), and the pidfile exists. That's why I'm thinking the script simply did not capture the pid. Is there something in this script that looks wrong?
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Naib
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PostPosted: Fri Aug 16, 2013 4:07 pm    Post subject: Reply with quote

Well that init script doesn't have a stop or check, so I guess it is inheriting.
The last time I ran into something like this it was downto a script launching the actual process so its PID isn't valid for the running process.

also this should be in programming
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audiodef
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PostPosted: Fri Aug 16, 2013 4:20 pm    Post subject: Reply with quote

I'm afraid I'm not much of an expert with writing init scripts. Should I not inherit? If so, what would be the best way to write my own stop() and restart()? How does launching an actual process make the pid invalid for the running process? Isn't the actual process supposed to be launched?
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Naib
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PostPosted: Fri Aug 16, 2013 4:33 pm    Post subject: Reply with quote

looking in my init.d directory it looks like they all define their own stop method:

Quote:
stop() {
ebegin "Stopping Tor"
start-stop-daemon --stop --pidfile "${PIDFILE}" --exec /usr/bin/tor -- --PidFile "${PIDFILE}"
eend $?



I am only postulating whether the process you are launching is the actual process that does the work. Quite a few processes have a wrapper script/program that kind of prepares environments etc.
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audiodef
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PostPosted: Fri Aug 16, 2013 4:49 pm    Post subject: Reply with quote

It is launching the actual process - no wrapper here.

Thank you! Adding a stop() to the script is exactly what I needed. Now the script simply works as expected. I appreciate this very much. This has been bugging me for a while now. :)

Just needed to add, at the end:

Code:

stop() {
ebegin "Stopping Liquidsoap..."
start-stop-daemon --stop --pidfile "${pidfile}" --exec ${command} -- --PidFile "${pidfile}"
eend $?
}

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John R. Graham
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PostPosted: Fri Aug 16, 2013 9:31 pm    Post subject: Reply with quote

Moved from Off the Wall to Portage & Programming. Seems to fit better here.

- John
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