Question

I am working with someone on a data analysis project and we frequently document the steps we perform by putting them into small shell scripts. The problem is that I use bash and the other person uses csh. The other person has a habit of using source to run these scripts instead of executing them directly (this habit probably dates back to times when spawning an extra shell was an extravagent waste of resources, so it’s probably too entrenched to change) , and I want to have my scripts (which are, of course, bash scripts) simply stop with a message reminding the user to run them with bash instead of csh when this person sources them from within csh. At the same time, I would like them to continue to function as bash scripts.

So is there some code I can put at the beginning of my scripts that is a no-op in bash but will signal an error and cancel the execution of the rest of the file (but not kill the shell itself) when sourced from cshell?

Answer 1

This is harder than I thought due to csh’s ancient variable substitution flavor. However, $?BASH_VERSION expands to 0 (not set) in csh and to 0BASH_VERSION (or whatever the last commands’ RV was) in bash. So,

test "$?BASH_VERSION" = 0 && exit 1

should do the trick.