Various ways to make a script know about programs.

Wait for a program to exit ∞

See wait-for-exit.sh

(Xdialog)

\Xdialog --yesno 'test' 5 40 &
checkpid=$!
\wait $checkpid &> /dev/null
\echo "Xdialog has ended."

Is a program running? ∞

is-program-running？.sh

• launch an application
• begin a timer
• after the timer elapses, check if the application is still running
• if still running, perform action A

• if no longer running, perform action B

The basic solution is kill -0 $pid to see if a pid would be killable. To be killable it has to exist. This can be implemented like so:

timeout=10
 
timeout_run(){
  \Xdialog --yesno 'test' 5 40 &
  checkpid=$!
}
 
timeout_running(){
  \echo "It's still running\!"
}
 
timeout_not_running(){
  \echo "It's no longer running."
}
 
timeout_run
\sleep $timeout
\kill -0 $checkpid &> /dev/null
if [ $? -eq 0 ]; then
  timeout_running
else
  timeout_not_running
fi

Is a program hung? ∞

is-program-hung？.sh

This was originally designed as a way for the script to learn if an application was hung.

I leverage xkill, which is almost universally installed and is very easy to interact with. I could communicate with my script by right-clicking to have xkill do nothing and exit gracefully, or I could simply left-click with xkill to kill the misbehaving application.

timeout=10
 
timeout_run(){
  \Xdialog --yesno 'test' 5 40 &
}
 
timeout_program() {
  \xkill > /dev/null &
  checkpid=$!
}
 
timeout_running(){
  \echo "It's still running\!"
}
 
timeout_not_running(){
  \echo "It's no longer running."
}
 
timeout_run
timeout_program
\sleep $timeout
\kill -0 $checkpid &> /dev/null
if [ $? -eq 0 ]; then
  timeout_running
else
  timeout_not_running
fi