Cfrtjryk

I've created the following script on Ubuntu that can pause and start a specific process:

#!/bin/bash



loopProcess () {

   COUNTER=0

   while [  true ]; do

      echo $COUNTER

      sleep 1

      let COUNTER=COUNTER+1 

   done

}



loopProcess &

pidLoopProcess=$(echo $!)



while [  true ]; do

   read -p "" state

   if [ "$state" == 'a'  ]; then

      echo "Process is running"

      kill -CONT "$pidLoopProcess"

   elif [ "$state" == 'b'  ]; then

      echo "Process is sleeping"

      kill -STOP "$pidLoopProcess"

   fi  

done

Demonstration of how it works:

I'd like to know if it's possible to check when a specific process is running or sleeping using the command line. The pseudocode would be something like this:

if [ "$(StatePID $pidLoopProcess)" == 'sleeping'  ]; then

    ## do something

fi

I know that with this script I could just declare some global variables and use them as flags... But I want to know if there's a command line tool that does that for me. Is there? Is it possible?

On Linux, you can use this to get the status of a process with a given PID:

ps -o stat= $pid

That returns T when a process is stopped. So, assuming you are on a Linux system, you could do something like this:

if [ "$(ps -o stat= $pid)" = "T" ]; then 

    echo stopped

else 

    echo not stopped

fi

A full list of process state codes is given in man ps:

PROCESS STATE CODES

       Here are the different values that the s, stat and state output specifiers

       (header "STAT" or "S") will display to describe the state of a process:



               D    uninterruptible sleep (usually IO)

               I    Idle kernel thread

               R    running or runnable (on run queue)

               S    interruptible sleep (waiting for an event to complete)

               T    stopped by job control signal

               t    stopped by debugger during the tracing

               W    paging (not valid since the 2.6.xx kernel)

               X    dead (should never be seen)

               Z    defunct ("zombie") process, terminated but not reaped by its parent



   For BSD formats and when the stat keyword is used, additional characters may be

   displayed:



           <    high-priority (not nice to other users)

           N    low-priority (nice to other users)

           L    has pages locked into memory (for real-time and custom IO)

           s    is a session leader

           l    is multi-threaded (using CLONE_THREAD, like NPTL pthreads do)

           +    is in the foreground process group