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How to Write Linux Init Scripts Based on LSB Init Standard

LSB stands for Linux Standard Base.

LSB was started by Linux Foundation to reduce the difference between several Linux distributions, and thereby reducing the cost involved in porting between different distributions. Init scripts are one among them to be standardized.

In this article, we will see how to write an Init script that conforms to LSBInit Standard.

Init scripts are used to start|stop a software|service. For example, if you are using postgresql software, we will have a Init script named ‘/etc/init.d/postgresql’ which can be used to ‘start|stop|restart|reload|force-reload|status’.

LSB-compliant init scripts need to:

  • Provide at-least ‘start, stop, restart, force-reload, and status’
  • Return Proper exit code
  • Document run-time dependencies

Optionally, they can use init.d functions like “log_success_msg”, “log_failure_msg” etc.. to log the messages.

LSB provides default set of functions which is in /lib/lsb/init-functions. We can make use of those functions in our Init scripts. All the Init process by default will log the pid of the process in a file under /var/run/ directory. This is useful for the Init scripts to find the status of the process.

Now let’s start writing a Init script. First we need to add a header to the Init script, which looks like,

# Provides:          my_daemon
# Required-Start:    postgresql networking
# Required-Stop:     postgresql networking
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: This is a test daemon
# Description:       This is a test daemon
#                    This provides example about how to
#                    write a Init script.

Provides specifies what is the facility provided by this Init script. The name should be unique.

Required-start specifies the set of facilities that should be started before starting this service. In our case, postgresql and networking has to be started before starting my_daemon. Remember, here ‘postgresql’ will have a separate Init script which says ‘Provides: postgresql’. This ensures dependency based booting. Based on this dependency, the ‘inserv’ command or ‘update-rc.d’ will put the entries in run-level directories with appropriate sequence number. For example, the entries can be like follows


Which indicates, networking will be started first, then postgresql and then my_daemon.

To know more about run-levels, refer to stage#6 (which is runlevel) of Linux boot process.

Required-Stop specifies the list of facilities that has to be stopped only after stopping this facility. Here only after my_daemon is stopped, the postgresql and networking facilities will be stopped.

Default-Start Default-Stop defines the run-levels in which the service has to be started or stopped.

Short-Description and Description are used to give some description with regard the to the facility provided. Description can span across multiple lines, Short-Description is limited to single line.

Let’s look at an actual Init script.

# Provides:          my_daemon
# Required-Start:    postgresql networking
# Required-Stop:     postgresql networking
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: This is a test daemon
# Description:       This is a test daemon
#                    This provides example about how to
#                    write a Init script.

# Using the lsb functions to perform the operations.
. /lib/lsb/init-functions
# Process name ( For display )
# Daemon name, where is the actual executable
# pid file for the daemon

# If the daemon is not there, then exit.
test -x $DAEMON || exit 5

case $1 in
  # Checked the PID file exists and check the actual status of process
  if [ -e $PIDFILE ]; then
   status_of_proc -p $PIDFILE $DAEMON "$NAME process" && status="0" || status="$?"
   # If the status is SUCCESS then don't need to start again.
   if [ $status = "0" ]; then
    exit # Exit
  # Start the daemon.
  log_daemon_msg "Starting the process" "$NAME"
  # Start the daemon with the help of start-stop-daemon
  # Log the message appropriately
  if start-stop-daemon --start --quiet --oknodo --pidfile $PIDFILE --exec $DAEMON ; then
   log_end_msg 0
   log_end_msg 1
  # Stop the daemon.
  if [ -e $PIDFILE ]; then
   status_of_proc -p $PIDFILE $DAEMON "Stoppping the $NAME process" && status="0" || status="$?"
   if [ "$status" = 0 ]; then
    start-stop-daemon --stop --quiet --oknodo --pidfile $PIDFILE
    /bin/rm -rf $PIDFILE
   log_daemon_msg "$NAME process is not running"
   log_end_msg 0
  # Restart the daemon.
  $0 stop && sleep 2 && $0 start
  # Check the status of the process.
  if [ -e $PIDFILE ]; then
   status_of_proc -p $PIDFILE $DAEMON "$NAME process" && exit 0 || exit $?
   log_daemon_msg "$NAME Process is not running"
   log_end_msg 0
  # Reload the process. Basically sending some signal to a daemon to reload
  # it configurations.
  if [ -e $PIDFILE ]; then
   start-stop-daemon --stop --signal USR1 --quiet --pidfile $PIDFILE --name $NAME
   log_success_msg "$NAME process reloaded successfully"
   log_failure_msg "$PIDFILE does not exists"
  # For invalid arguments, print the usage message.
  echo "Usage: $0 {start|stop|restart|reload|status}"
  exit 2

The above script basically provides a template for writing LSBInit scripts. You can change the DAEMON,PIDFILE,NAME variables, and the header to make this script, fit to your own programs.

To know more about the functions provided by the LSB, please refer to InitScript Functions

Once the Init script is done, in order to make the script to start or stop automatically, execute the following command. This will add appropriate ‘S’ and ‘K’ entries in the given run-levels. This will also add appropriate sequence number by considering the dependencies.

update-rc.d filename defaults
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Comments on this entry are closed.

  • Pierre B. March 16, 2012, 2:31 am


    It’s been some time that i wanted to have a more detailed look at LSB scripts writing, it is now easier thanx to you!

  • Suresh Danda March 16, 2012, 2:32 am

    Excellent Bro……!

    Thanks for being like Geek and making Geeks.

  • Jalal Hajigholamali March 16, 2012, 3:02 am


    Thanks a lot, very nice article

  • tasos March 16, 2012, 4:21 am

    Great article

  • Lakshmanan Ganapathy March 16, 2012, 8:09 am

    Thank u all guys…

  • Mustapha Oldache March 17, 2012, 12:03 pm

    Genius article about things we dont mind.

  • Julien March 21, 2012, 9:57 am

    Great explaination ! wanted to learn that one day. Checked

  • Shantanu May 19, 2012, 2:30 pm

    Good article to get started with init script..!
    Can you mention distro name, distro version and LSB release for which this example script is written? I can’t seem to find some of the functions you have used, e.g. ‘log_daemon_msg’ and ‘status_of_proc’ either in ‘/lib/lsb/init-functions’ on CentOS 6.2 or refspec for LSB 3.1.0.

  • Mike Rogers July 1, 2012, 2:01 pm

    Thanks for the article – I notice in the status) option you dont return an exit status of 3 if the process is not running. This article suggest that in an init script that is lsb compliant, process not running should return ‘ 3 program is not running’ rather than 0. This article is specific to my current learning.

  • Venadan August 29, 2012, 10:00 am

    Excelelnt article. Was looking for some thing like this explains in detail..

  • Lakshmanan Ganapathy October 12, 2012, 10:07 am

    @Mike Rogers

    Thanks for pointing it out Mike.

  • Victory January 19, 2013, 7:08 am

    Great post, i put the script template to good use.

    One little gotcha i found is that line

    start-stop-daemon –start –quiet –oknodo –pidfile $PIDFILE –exec $DAEMON

    Expects the DAEMON to create a pid file, which mine was just a shell script and did not, i also had to force it to the background

    I used the -b and –make-pidfile options to fix this.

    start-stop-daemon –start -b –make-pidfile –quiet –oknodo –pidfile $PIDFILE –exec $DAEMON

  • pavan October 2, 2013, 12:37 am

    thanks for the nice and neat article

  • Senthil February 11, 2014, 10:23 pm

    Thanks. As usual, well explained!

  • Avinita February 3, 2015, 4:06 am

    This is helpful. Thank you!

  • Anonymous February 23, 2015, 12:16 am

    where is status_of_proc functions etc. defined ? I don’t see it in /lib/lsb/init-functions !!

  • Sepahrad Salour March 1, 2015, 11:55 am

    Thanks for the nice article…

  • Lukas June 11, 2015, 7:21 am

    Thanks for your template! Great work!

    Hint: typo “stoppping” at line ~49

  • Chris June 26, 2017, 10:23 am

    If this article is supposed to be about “LSB Standard” init scripts, why would you use an example that contains distribution-specific (in this case Debian/Ubuntu only) commands like “start-stop-daemon” and “status_of_proc” ?

  • Krishna April 2, 2019, 1:13 am

    Hi Team,

    I have once init.d script which needs to started before network service.

    Actually i have IP change info in that script so after running that script network service should start

    So that the new IP will assign to my system while booting itself.

    Could you help me.