Tuesday, May 31, 2016

Gee wilickers

I have a common command-line pattern I grew tired of typing. An example

$ mvn verify | tee verify.out

I use this pattern so often as I want to both watch the build on screen, and have a save file to grep when something goes wrong. Sometimes I also find myself telling the computer:

$ mvn verify | tee verify.out
$ mv verify.out verify-old.out
$ $EDITOR pom.xml
$ mvn verify | tee verify.out
$ diff verify-old.out verify.out

I want to see what changed in my build. But ... too much typing! So I automated with gee, a mashup of git and tee. You can think of it as source control for <STDOUT>.

Now I can type:

$ gee -o verify.out mvn verify
$ gee -g git diff HEAD^  # Did build output change?

How does it work? gee keeps a git repository in a hidden directory (.gee), committing program output there using tee. It follows simple conventions for file name and commit message (changeable with flags), and accepts <STDIN>:

$ mvn verify | gee -o verify.out -m 'After foobar edit'
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