Can a shell script set environment variables of the calling shell? [duplicate]

Question

I'm trying to write a shell script that, when run, will set some environment variables that will stay set in the caller's shell.

setenv FOO foo 

in csh/tcsh, or

export FOO=foo 

in sh/bash only set it during the script's execution.

I already know that

source myscript 

will run the commands of the script rather than launching a new shell, and that can result in setting the "caller's" environment.

But here's the rub:

I want this script to be callable from either bash or csh. In other words, I want users of either shell to be able to run my script and have their shell's environment changed. So 'source' won't work for me, since a user running csh can't source a bash script, and a user running bash can't source a csh script.

Is there any reasonable solution that doesn't involve having to write and maintain TWO versions on the script?

Answer 1

Use the "dot space script" calling syntax. For example, here's how to do it using the full path to a script:

. /path/to/set_env_vars.sh 

And here's how to do it if you're in the same directory as the script:

. set_env_vars.sh 

These execute the script under the current shell instead of loading another one (which is what would happen if you did ./set_env_vars.sh). Because it runs in the same shell, the environmental variables you set will be available when it exits.

This is the same thing as calling source set_env_vars.sh, but it's shorter to type and might work in some places where source doesn't.