fix shellcheck issues in our shell scripts

Throughout our repos we have a number of shell scripts linked to release and build mainly.

These scripts are not checked for issues and or tested. I ran  shellcheck over some of them and a number of possible issues popped up. We should run the tool over all repos and the shell scripts we have and fix the issues found.

Lots of them are around variable quoting that is missing and the use of deprecated  back-ticked `cmd` substitution which are not portable. We do not have a standard set for these and have mixed them in our use.