Usually when you execute some shell script and you need to reuse the output for another shell script or internal you need to do something like:

sh('git rev-parse HEAD > GIT_COMMIT')
git_commit=readFile('GIT_COMMIT')

This is ok, but maybe we could provide something like:

git_commit = sho('git rev-parse HEAD')

sho = shell output
which basically takes the output and put it in a var.

Another option could be adding a parameter to sh that indicates that we want to capture the outout and return it back.