Exploring code and its history
For my own repositories, I like to use gitx on my Mac to explore the commit history.
But, of course, you can also just poke around github itself.
And you can do a lot of things from the command line, say to look at
the combined changes to a file that were made over the last year.
github page about
Each commit is assigned a “hash tag” which is a unique
sequence of letters and numbers, like
When you refer to these hash tags, you can just use an initial substring,
4d9fe, that is unique to your repository.
For my R/qtl package, I like to tag particular commits by the version number of the package. Then I can use my assigned tag in place of the less memorable hash tag.
To assign a tag, use something like
git tag -a -m "Tagging version 1.28-5" 1.28-5
To push the tags to github, you need to use
git push --tags
To delete a tag, use
git tag -d 1.28-5
and then you need to remove the tag from github
git push origin :refs/tags/1.28-5
Uses of diff
To see all of the changes since the last commit, type
To see all of the changes since a given commit, type
git diff [commit]
Where in place of
[commit] you use the initial part of a hash tag,
5fb8045, or a tag you’ve created, like
git diff 5fb8045 git diff 1.22-21
To see all of the changes to a given file since a given commit, type
git diff [commit] [file]
git diff 1.22-21 R/scanone.R
To see all of the changes between two revisions, type something like
git diff 1.22-21 1.23-16
And again you can use this for a particular file:
git diff 1.22-21 1.23-16 inst/STATUS.txt
git diff has a ton of options; see the manual page:
git diff --help
For example, you can get a brief summary of which files were changed with
git diff 1.22-21 1.23-16 --stat
If you use gitx, you can use it to view the differences; use a pipe:
git diff 1.22-21 1.23-16 | gitx
Next: Branching and merging