shell script, for loop, does loop wait for execution of the command to iterate

Assuming that you haven't background-ed the command, then yes.

For example:

for i in {1..10}; do cmd; done

waits for cmd to complete before continuing the loop, whereas:

for i in {1..10}; do cmd &; done

doesn't.

If you want to run your commands in parallel, I would suggest changing your loop to something like this:

for m in "${mode[@]}" do     "$perlExecutablePath" "$perlScriptFilePath" --owner "$j" -rel "$i" -m "$m" &done

This runs each command in the background, so it doesn't wait for one command to finish before the next one starts.

An alternative would be to look at GNU Parallel, which is designed for this purpose.

Using GNU Parallel it looks like this:

parallel $perlExecutablePath $perlScriptFilePath --owner $j -rel $i -m {} ::: "${mode[@]}" 

GNU Parallel is a general parallelizer and makes is easy to run jobs in parallel on the same machine or on multiple machines you have ssh access to. It can often replace a for loop.

If you have 32 different jobs you want to run on 4 CPUs, a straight forward way to parallelize is to run 8 jobs on each CPU:

GNU Parallel instead spawns a new process when one finishes - keeping the CPUs active and thus saving time:

Installation

If GNU Parallel is not packaged for your distribution, you can do a personal installation, which does not require root access. It can be done in 10 seconds by doing this:

(wget -O - pi.dk/3 || curl pi.dk/3/ || fetch -o - http://pi.dk/3) | bash

For other installation options see http://git.savannah.gnu.org/cgit/parallel.git/tree/README

Learn more

See more examples: http://www.gnu.org/software/parallel/man.html

Watch the intro videos: https://www.youtube.com/playlist?list=PL284C9FF2488BC6D1

Walk through the tutorial: http://www.gnu.org/software/parallel/parallel_tutorial.html

Sign up for the email list to get support: https://lists.gnu.org/mailman/listinfo/parallel