Ruby

Gems

To see the docs for the gems you have installed (esp. gems in a gemset), start the server using gem server and then go to http://localhost:8808/

Git

diff

git diff -M - the -M flag tells git to detect file moves - so you can see what you changed in addition to renaming a file.

git diff -b - ignore changes that are only changes in white space.

add

git add -u puts changes in files it already knows about into the index but does not add untracked files. git commit -a is similar in that it does not commit untracked files but commits changes (modifications or file removals) to files it already knew about.