Run program in UNIX and make pidfile for it ·

We sometime want to run a program and after than stop it.

For example, at boot time, we start an selenium. But after that, we want to stop it.

The question is, how we could stop it? One approach is using ps -ef | grep command. But it hard to match exactly program we want to stop. I think the correct way is using pidfile. pidfile is the file which store a process id (the process id of program we start)

This post will tell you 2 ways to create pid file

1. Using `start-stop-daemon` tool

Syntax of start-stop-daemon is

$> start-stop-daemon --start --chuid <username> --background \
     --make-pidfile --pidfile /var/run/<pidfile>.pid --exec $PROGRAM -- $PROGRAM-ARGUMENT

More details about program and its parameters

  `--chuid username`: set user you want to run program in.
        (It is best practice if we dont run it with root access)
  `--backgroud`: make program run in background
  `--make-pidfile`: force program to create pidfile
        (sometime it doesnot work. check document of `start-stop-daemon` for more details)
  `--pidfile`: specify pidfile for the program
  `$PROGRAM-ARGUMENT`: is ARGUMENT for the program

Example is with selenium

SELENIUM_PROGRAM=/usr/bin/java
SELENIUM_OPTS="-jar /home/vagrant/selenium-server-standalone-2.24.1.jar"
SELENIUM_PID_NAME=selenium
start-stop-daemon --start --chuid vagrant --make-pidfile --background --pidfile \
    /var/run/$SELENIUM_PID_NAME.pid --exec $SELENIUM_PROGRAM -- $SELENIUM_OPTS

2. Using bashscript

Bashscript also support a method $! to get process id of last command

$> python &
$> echo $!
4035

So, if we want to start our selenium server and make pidfile, we can write a script like this

SELENIUM_PROGRAM=/usr/bin/java
SELENIUM_OPTS="-jar /home/vagrant/selenium-server-standalone-2.24.1.jar"
SELENIUM_PID_NAME=selenium
SELENIUM_LOG_FILE=selenium.logfile
su -c "$SELENIUM_PROGRAM $SELENIUM_OPTS 2>&1 >>$SELENIUM_LOG_FILE &" vagrant
PID=$!
echo $PID > $SELENIUM_PID_NAME.pid

3. Stop process right way

Now, if you want to stop a program which process id was store in pidfile, it quite easy

# using cat and xargs and kill
$> cat <pidfile> | xargs kill

# using start-stop-daemon tool again
$> start-stop-daemon --stop --pid <pidfile>

Menu

1. Using start-stop-daemon tool

2. Using bashscript

3. Stop process right way

1. Using `start-stop-daemon` tool