Most of the times when we need to run some Java, Node.js or python program in background, so it could stay running even after you leave console all we do is put “&” in the end of the command.<\/p>\n
The problem here is that when you leave the bash shell your process will become “Orphan” and it’s up to the OS if INIT should adopt the process or kill the process.<\/p>\n To fix this we can force the process to be detached from your shell and become child process of INIT by putting nohup in front of command.<\/p>\n It’s all good for testing purposes, but services are supposed to run as \u201cdaemons\u201d under some service supervisor. You can find many service supervisors with which you manage your services on Linux and we will cover few of the defaults that come\u00a0with Linux.<\/p>\n a.<\/strong> auto start\/stop the service on startup\/shutdown Modify the script according to your setup:<\/p>\n [js]author "nitin" start on started networking # Automatically Respawn a process if fails, try max 5 times in 60 sec then give up # Open files Limit env APPUSER="admin" script post-stop script Check the configuration: Reload New configuration: Check is service is known to Upstart: Start the service with: Note:<\/strong> For any errors look into \/var\/log\/syslog and \/var\/log\/upstart\/*<\/p>\n Modify the script according to your setup.<\/p>\n [js]#!\/bin\/sh<\/p>\n ### BEGIN INIT INFO NAME="java-app" # Include functions start() { #We need this function to ensure the whole process tree will be killed stop() { status() { case "$1" in exit 0[\/js]<\/p>\n Make sure the script is executable: Enable the service to auto start in runlevel 2345: Start the service with: Modify the parameter according to your setup: [js]#!\/bin\/sh # Source function library. # Source networking configuration. # Check that networking is up. USER="admin" LOGPATH=$(dirname $LOGFILE)<\/p>\n start() { echo -n $"Starting $APPNAME: " stop() { restart() { rh_status() { rh_status_q() { case "$1" in Make sure the script is marked as executable: Enable the service to auto start at runlevels 2345: Start the service with: This is how simple it is to daemonize a process. In my next blog, I will talk about more interesting features available in Linux OS.<\/p>\n","protected":false},"excerpt":{"rendered":" Most of the times when we need to run some Java, Node.js or python program in background, so it could stay running even after you leave console all we do is put “&” in the end of the command. $java -jar SimpleService.jar & The problem here is that when you leave the bash shell your […]<\/p>\n","protected":false},"author":747,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"iawp_total_views":49},"categories":[2348],"tags":[248,3290,3291,260,3292,3287,3289,3288],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/posts\/33915"}],"collection":[{"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/users\/747"}],"replies":[{"embeddable":true,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/comments?post=33915"}],"version-history":[{"count":0,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/posts\/33915\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/media?parent=33915"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/categories?post=33915"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/tags?post=33915"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}$java -jar SimpleService.jar &<\/code><\/p>\n$nohup java -jar SimpleService.jar &<\/code><\/p>\nWhy do you need it ?<\/h3>\n
\nb.<\/strong> controlling which service should start first
\nc.<\/strong> controlling which service should stop first is equally important
\nd.<\/strong> INIT controlled processes directly which provides more options like respawn, post-start, etc..<\/p>\nUbuntu services using Upstart<\/h3>\n
$sudo vi \/etc\/init\/java-app.conf<\/code><\/p>\n
\ndescription "start and stop java-app for Ubuntu (upstart)"
\nversion "1.0"<\/p>\n
\nstop on runlevel [!2345]<\/p>\n
\nrespawn
\nrespawn limit 5 60<\/p>\n
\nlimit nofile 32768 32768<\/p>\n
\nenv APPBIN="\/usr\/bin\/java"
\nenv APPARGS="-jar \/opt\/app\/SimpleService.jar"<\/p>\n
\n exec su – $APPUSER -c "$APPBIN $APPARGS"
\nend script<\/p>\n
\n sleep 2
\nend script[\/js]<\/p>\n
\n$init-checkconf \/etc\/init\/java-app.conf<\/code><\/p>\n
\n$sudo initctl reload-configuration<\/code><\/p>\n
\n$sudo initctl list |grep java<\/code><\/p>\n
\n$sudo start java-app<\/code><\/p>\nDebian and Ubuntu services using SysVinit<\/h3>\n
$sudo vi \/etc\/init.d\/java-app<\/code><\/p>\n
\n# Provides: daemon
\n# Required-Start: $local_fs $network $syslog
\n# Required-Stop: $local_fs $network $syslog
\n# Default-Start: 2 3 4 5
\n# Default-Stop: 0 1 6
\n# Short-Description: Java-app
\n# Description: Java-app start-stop-daemon – Debian
\n### END INIT INFO<\/p>\n
\nPATH="\/usr\/local\/sbin:\/usr\/local\/bin:\/sbin:\/bin:\/usr\/sbin:\/usr\/bin"
\nAPPDIR="\/opt\/app"
\nAPPBIN="\/usr\/bin\/java"
\nAPPARGS="-jar \/opt\/app\/SimpleService.jar"
\nUSER="admin"
\nGROUP="admin"<\/p>\n
\nset -e
\n. \/lib\/lsb\/init-functions<\/p>\n
\n printf "Starting ‘$NAME’… "
\n start-stop-daemon –start –chuid "$USER:$GROUP" –background –make-pidfile –pidfile \/var\/run\/$NAME.pid –chdir "$APPDIR" –exec "$APPBIN" — $APPARGS || true
\n printf "done\\n"
\n}<\/p>\n
\nkilltree() {
\n local _pid=$1
\n local _sig=${2-TERM}
\n for _child in $(ps -o pid –no-headers –ppid ${_pid}); do
\n killtree ${_child} ${_sig}
\n done
\n kill -${_sig} ${_pid}
\n}<\/p>\n
\n printf "Stopping ‘$NAME’… "
\n [ -z `cat \/var\/run\/$NAME.pid 2>\/dev\/null` ] || \\
\n while test -d \/proc\/$(cat \/var\/run\/$NAME.pid); do
\n killtree $(cat \/var\/run\/$NAME.pid) 15
\n sleep 0.5
\n done
\n [ -z `cat \/var\/run\/$NAME.pid 2>\/dev\/null` ] || rm \/var\/run\/$NAME.pid
\n printf "done\\n"
\n}<\/p>\n
\n status_of_proc -p \/var\/run\/$NAME.pid "" $NAME && exit 0 || exit $?
\n}<\/p>\n
\n start)
\n start
\n ;;
\n stop)
\n stop
\n ;;
\n restart)
\n stop
\n start
\n ;;
\n status)
\n status
\n ;;
\n *)
\n echo "Usage: $NAME {start|stop|restart|status}" >&2
\n exit 1
\n ;;
\nesac<\/p>\n
\n$chmod +x \/etc\/init.d\/java-app<\/code><\/p>\n
\n$update-rc.d java-app defaults<\/code><\/p>\n
\n$service java-app start<\/code><\/p>\nCentOS\/Redhat services using SysVinit<\/h3>\n
\n$sudo vi \/etc\/init.d\/example<\/code><\/p>\n
\n#
\n# example start stop daemon for CentOS (sysvinit)
\n#
\n# chkconfig: – 64 36
\n# Default-Start: 2 3 4 5
\n# Default-Stop: 0 1 2 3 4 6
\n# Required-Start:
\n# description: java-app start stop daemon for CentOS
\n# processname: java-app
\n# pidfile: none
\n# lockfile: \/var\/lock\/subsys\/java-app<\/p>\n
\n. \/etc\/rc.d\/init.d\/functions<\/p>\n
\n. \/etc\/sysconfig\/network<\/p>\n
\n[ "$NETWORKING" = "no" ] && exit 0<\/p>\n
\nAPPNAME="java-app"
\nAPPBIN="\/usr\/bin\/java"
\nAPPARGS="-jar \/opt\/app\/SimpleService.jar"
\nLOGFILE="\/var\/log\/$APPNAME\/error.log"
\nLOCKFILE="\/var\/lock\/subsys\/$APPNAME"<\/p>\n
\n [ -x $prog ] || exit 5
\n [ -d $LOGPATH ] || mkdir $LOGPATH
\n [ -f $LOGFILE ] || touch $LOGFILE<\/p>\n
\n daemon –user=$USER "$APPBIN $APPARGS >>$LOGFILE &"
\n RETVAL=$?
\n echo
\n [ $RETVAL -eq 0 ] && touch $LOCKFILE
\n return $RETVAL
\n}<\/p>\n
\n echo -n $"Stopping $APPNAME: "
\n killproc $APPBIN
\n RETVAL=$?
\n echo
\n [ $RETVAL -eq 0 ] && rm -f $LOCKFILE
\n return $RETVAL
\n}<\/p>\n
\n stop
\n start
\n}<\/p>\n
\n status $prog
\n}<\/p>\n
\n rh_status >\/dev\/null 2>&1
\n}<\/p>\n
\n start)
\n rh_status_q && exit 0
\n $1
\n ;;
\n stop)
\n rh_status_q || exit 0
\n $1
\n ;;
\n restart)
\n $1
\n ;;
\n status)
\n rh_status
\n ;;
\n *)
\n echo $"Usage: $0 {start|stop|status|restart}"
\n exit 2
\nesac[\/js]<\/p>\n
\n$sudo chmod +x \/etc\/init.d\/java-app<\/code><\/p>\n
\n$sudo chkconfig java-app on<\/code><\/p>\n
\n$sudo service java-app start<\/code><\/p>\n