Using this OF=$(ps fax | grep 'php-fpm: master process' | awk '{print $1}')  IDX=`expr index $OF ' '`I get an error. The results of the $OF variable are:27797 27495What is the error here? I think it has to do with how the variable is being passed into the expression. Also, have tried putting ' quotes around the $OF variable to no avail. That just returns 0 as not found.
Getting expr: syntax error on index
bash;shell;shell script
You should use pgrep to grep the Process ID of a process. This is the safest way there is. Some systems(legacy systems) don't have pgrep so you'd be forced to use something as ps.  In case you use ps You should consider the following. Your line uses grep and awk which is not necessary as you could handle all that using awk. of=$(ps fax | awk '/[p]hp-fpm: master process/{print $1}') As a side note. Don't use upper case for normal variable names. By convension, Environment variables are CAPITALIZED.  At this stage your variable $of will hold the process id of the php-fpm.  Since your question is not clear, I'm not sure what expr is doing there.