Git: Diff And History

More notes about using Git that I always forget. This set is about diffs and history.

Excluding Files In Diff

A useful incantation of git diff which can be used to exclude files in the diff output.

git diff -- ':!file/to/exclude.php' ':!file/to/exclude.php'

This can be extended to glob patterns as well. For example, an incantation that can be used to ignore all generated mock files and gRPC files in a Go project:

git diff -- ':!*.pb.go' ':!mock'

Source: Stack Overflow

Showing Only Changed Files In Git Log

This technique shows only the changed files in a git log call without having to show the entire patch:

git log --name-only ...

Showing Specific Revision Of A File

To display the contents of a file at a given revision in Git, run the following command:

git show <revision>:<filename>

For example, to view the version of “README.md” on the dev branch:

git show dev:README.md

There is an alternative form of this command that will show the changes applied to that file as part of the commit:

git show <revision> -- <filename>

This can be used alongside the log command to work out what happened to a file that was deleted.

First, view the history of the file. You are interested in the ID before the commit that deleted the file: attempting to run git show using the deletion commit ID it will result in nothing being shown.

$ git log -- file/that/was/deleted
commit abc123
Author: The Deleter <deleter@example.com>
Date:   XXX

    Deleted this file.  Ha ha ha!

commit beforeCommit
Author: File Changer <changer@example.com>
Date:   XXX

    Added a new file at file/that/was/deleted

Then, use git show to view the version before it was deleted:

git show beforeCommit:file/that/was/deleted