Shell Programming and Scripting

For checking the process ID ,I have to use ps -ef | grep pid or ps -p pid. What is the assurance that this commands won't fail.Any way its landed up to the same position again right?

Thanks in advance

Never seen "ps -p PID" misbehave, only "ps -ef" on a heavily loaded system.

I have inherited an alert script which counts one type of process every 5 minutes based on "ps -ef". Every few days the alert fires spuriously with a number too high or too low. If the alert fires again, I look.

My system-supplied standard init scripts mostly use "ps -e" piped to a clever awk to find the PID of a process. Might be worth a trawl through your system's init scripts to see what techniques they use. Personally I would find out the PID at the time of starting the process and record that PID in a file with view to using "ps -p PID".