Btukfyl

I am trying to create an init script for a program in bash. (rhel6)

It checks for the processes first. If processes are found it will echo that program is already online and if not it'll move on to to start the program as a certain user by using launch script. After doing that it should tail the log file of the program and check for a string of words together. If the words are found it should kill tail and echo that program is online.

Here's the start segment.

prog=someProg

user=someUser

threadCount=$(ps -ef | grep $prog |grep -v 'grep' |awk '{ print $2 }'| wc -l)



startb() {

  if [ "$threadCount" -eq 2 ]; then

    echo "$prog already online."

  else

    echo "Bringing $prog online."

    su $user -c "/path/to/start/script.sh"

    tail -f /path/to/$prog/log/file |

      while IFS=$'n' read line

        do

          if [[ $line == *started up and registered in* ]]; then

            pkill tail

            echo "$prog now online."

          fi

        done

  fi

}

My problems:

1. The variable $prog doesn't get picked in $threadcount no
   matter how I try. (with single and double quotes)


2. The logic about tailing the log file works randomly. Some times it
   just works perfect. It tails and waits till the string is found
   before echoing program is online and at times it just starts script
   and then echoes that program is online without the tail or wait.

It's unpredictable. I implemented the same logic in stop segment too to monitor log and then echo but even that works the same way as start. Just random.

I am sure that this might look dumb and broken. This is made by picking pieces here and there with my beginner bash skills.

Thanks in advance for suggestions and help.

I can't reproduce the error you are experiencing with the "grep $prog"...sorry.

But for the other part.

1. I will assume that the script starting your program, the line with su, is starting something in background and that the script end by itself. If not, your example will wait indefinitely.




2. Could be a personal preference, but when I'm using something like tail to verify lines, I use a named pipe (mkfifo).

That would give something like :

# Getting the tail in background

tail -f /path/to/$prog/log/file > some_fifo &

# Getting the tail PID

tailPID=$!



while read line; do #You don't need to modify/use IFS here.

     if [[ $line == *started up and registered in* ]]; then

           kill -15 $tailPID #since you know the PID you won't kill another tail

           echo "$prog now online."

           break # don't like the possibility, even remote, of an infinite loop :)

     fi

done < some_fifo #reading from the named pipe

Hope it can help you