Twisted IT paired

UPDATE: To use it with systemd, create a file in (Debian):
/lib/systemd/system/screen-startup.service
containing:

[Unit]
Description=Screen startup service
After=network.target

[Service]
Type=oneshot
PIDFile=/run/screen-startup.pid
ExecStart=/usr/sbin/screen-startup start
ExecStop=/usr/sbin/screen-startup stop
#ExecReload=/usr/sbin/screen-startup restart
RemainAfterExit=yes


[Install]
WantedBy=multi-user.target

Then link it in etc:
#> ln -s /lib/systemd/system/screen-startup.service /etc/systemd/system/multi-user.target.wants/screen-startup.service
Then enable it:
#> systemctl enable screen-startup

Have you ever wondered how to startup your scripts in screen upon boot?
I've wondered for a while, googled few times and when I found nothing nice I wrote this simple script.

It has few nice features:

- can run screen as given user
- check if screen/session is not already started.
- clean ups stale pid files
- it's a debian startup script
- reads command and user to run as from config file in $CFG dir.
- sets session name as defined in config. !new!

Comments and bugs are welcome to valqk to lozenetz dt net

Sample config /etc/screen-startup/run_site.cfg:

SCRIPT=/path/to/cron/script.sh

USER=siteuser

SCREEN_NAME=site_cronjob

Script name: screen-startup

#!/bin/bash

# /etc/init.d/screen-startup

#

### BEGIN INIT INFO

# Provides:          screen-startup

# Required-Start:     screen-cleanup

# Required-Stop:	

# Default-Start:     2 3 4 5

# Default-Stop:      0 1 6

# Short-Description: Start daemon at boot time

# Description:       Enable service provided by daemon.

### END INIT INFO

[ -z "$CFG" ] || ! [ -d "$CFG" ] && CFG='/etc/screen-startup/';

! [ -d "$CFG" ] && echo "No config dir!" && exit 1;

# Carry out specific functions when asked to by the system

startScreen() {

    echo "Starting screens..."

    for script in $CFG/*.cfg;

    do

        ! [ -f "$script" ] && continue;

        SCRIPT=`grep SCRIPT= $script|cut -f2 -d=`;

        USER=`grep USER= $script|cut -f2 -d=`;

        SCREEN_NAME=`grep SCREEN_NAME= $script|cut -f2 -d=`;

        if [ -n "$SCRIPT" ] && [ -n "$USER" ]; then

            if [ "x${SCREEN_NAME}" = "x" ]; then

              sessName="`echo $SCRIPT|sed -e 's%/%_%g'`-$USER-AS"

            else

              sessName="${SCREEN_NAME}";

            fi

            if [ -f /var/run/screen/$sessName.pid ]; then

              sessPid=`cat /var/run/screen/$sessName.pid`;

              [ "x$sessPid" != "x" ] && [ `ps -p $sessPid|wc -l` -gt 1 ] && echo "$sessName alredy started ($sessPid)!!!" && continue;

              echo "cleaning stale pid file: $sessName.pid"

              rm /var/run/screen/$sessName.pid

            fi

            echo -n "Screen $SCRIPT for user $USER..."

            /bin/su -c "/usr/bin/screen -dmS $sessName $SCRIPT" $USER

            screenPid=`ps ax|grep "$sessName"|grep "$SCRIPT"|grep -v grep|awk '{print $1}'`

            echo $screenPid > /var/run/screen/$sessName.pid

            echo "done.";

        fi

    done

}

stopScreen() {

    echo "Stopping screens..."

    for script in $CFG/*.cfg;

    do

        ! [ -f "$script" ] && continue;

        SCRIPT=`grep SCRIPT= $script|cut -f2 -d=`;

        USER=`grep USER= $script|cut -f2 -d=`;

        SCREEN_NAME=`grep SCREEN_NAME= $script|cut -f2 -d=`;

        sessName="`echo $SCRIPT|sed -e 's%/%_%g'`-$USER-AS"

        if [ "x${SCREEN_NAME}" = "x" ]; then

          sessName="`echo $SCRIPT|sed -e 's%/%_%g'`-$USER-AS"

        else

          sessName="${SCREEN_NAME}";

        fi

        if [ -f  /var/run/screen/$sessName.pid ]; then

            pidOfScreen=`cat /var/run/screen/$sessName.pid|cut -f 1 -d' '`;

            pidOfBash=`cat /var/run/screen/$sessName.pid|cut -f 2 -d' '`;

            if [ "x$pidOfBash" != "x" ] && [ `ps -p $pidOfBash|wc -l` -lt 2 ]; then

                echo "Missing process $pidOfBash for screen $pidOfScreen. Cleaning up stale run file."

                rm /var/run/screen/$sessName.pid;

                continue;

            else

                echo -n "Screen: $SCRIPT for user $USER..."

                kill $pidOfBash $pidOfScreen;

                echo "done."

                rm /var/run/screen/$sessName.pid;

            fi

        fi

    done



}

case "$1" in

  start)

    startScreen;

    ;;

  stop)

    stopScreen;

    ;;

  restart)

    stopScreen;

    startScreen;

    ;;

  *)

    echo "Usage: $0 {start|stop|restart}"

    exit 1

    ;;

esac

exit 0

p.s. Edit: rev.1 of the script now supports SCREEN_NAME in config. When set you can resume screen with screen -s SCREEN_NAME (or part of it).