bash syntax used in sh script

On many unix systems `/bin/sh` is a bourne shell compatible on does not support the bash syntax used in `mjprof` script. either change the interpreter to `/bin/bash` or change the syntax to bourne shell.

e.g. on my laptop i got this when running mjprof:
`/home/avishai/tools/mjprof1.0/mjprof: 2: /home/avishai/tools/mjprof1.0/mjprof: Bad substitution`