Bash Job Control
Having already explored the possibilities of starting parallel processes using the Gnome window-manager, as described on my go page, it was high time to immerse myself, being the keyboard-addicted geek that I am, into doing the same by using just a simple terminal.
But what’s the point? In my case, it was a commit process with a revision-control system called foo. The commit is done with a script, and I wanted to make sure the project compiles OK before the actual commit.
This involves two quite long processes, which could nicely run parallel, one is composing the commit-message with an editor, and the other is the compilation. We shall go on with the commit after BOTH are finished. Oh, I nearly forgot, the commit shall be canceled, if the compilation fails!
I studied bash job-control a bit and then:
# The '&' character runs the command in the background # which in turn becomes job number 1, later referred to as %1. make & # Compose the commit-message in the foreground foo-status > CommitMessage mcedit CommitMessage # Wait for the make (job 1, alias %1) to complete, # check its exit status and abort if it's failed. # The 'wait' command's exit status is the same as the job's we wait for wait %1 if [ $? -ne 0 ]; then exit 1; fi # Do the commit foo-commit --message=CommitMessage rm CommitMessage
Try this with batch-files on Windows. Actually, you can do it with Cygwin. I’m sure Richard Stallman calls this platform GNU/Windows.
Bash is cool. Bourne Again Shell for Born Again Christians, that’s what I always say. Or as Master Foo put it once:
“There is more Unix-nature in one line of shell script than there is in ten thousand lines of C.”
