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diff --git a/docs/git/survival.md b/docs/git/survival.md new file mode 100644 index 0000000..60d1b62 --- /dev/null +++ b/docs/git/survival.md @@ -0,0 +1,81 @@ +# Git Survival Guide + +I think the `git` UI is pretty awful, and encourages using Git in ways that +will screw you. Here are a few things I've picked up that have saved my bacon. + +* You will inevitably need to understand Git's “internals” to make use of it + as an SCM tool. Accept this early. If you think your SCM tool should not + expose you to so much plumbing, [don't](http://mercurial.selenic.com) + [use](http://bazaar.canonical.com) [Git](http://subversion.apache.org). + * Git weenies will claim that this plumbing is what gives Git all of its + extra power. This is true; it gives Git the power to get you out of + situations you wouldn't be in without Git. +* `git log --graph --decorate --oneline --color --all` +* Run `git fetch` habitually. Stale remote-tracking branches lead to sadness. +* `git push` and `git pull` are **not symmetric**. `git push`'s + opposite operation is `git fetch`. (`git pull` is equivalent to `git fetch` + followed by `git merge`, more or less). +* [Git configuration values don't always have the best defaults](config). +* The upstream branch of `foo` is `foo@{u}`. The upstream branch of your + checked-out branch is `HEAD@{u}` or `@{u}`. This is documented in `git help + revisions`. +* You probably don't want to use a merge operation (such as `git pull`) to + integrate upstream changes into topic branches. The resulting history can be + very confusing to follow, especially if you integrate upstream changes + frequently. + * You can leave topic branches “real” relatively safely. You can do + a test merge to see if they still work cleanly post-integration without + actually integrating upstream into the branch permanently. + * You can use `git rebase` or `git pull --rebase` to transplant your + branch to a new, more recent starting point that includes the changes + you want to integrate. This makes the upstream changes a permanent part + of your branch, just like `git merge` or `git pull` would, but generates + an easier-to-follow history. Conflict resolution will happen as normal. +* Example test merge, using `origin/master` as the upstream branch and `foo` + as the candidate for integration: + + git fetch origin + git checkout origin/master -b test-merge-foo + git merge foo + # run tests, examine files + git diff origin/master..HEAD + + To discard the test merge, delete the branch after checking out some other + branch: + + git checkout foo + git branch -D test-merge-foo + + You can combine this with `git rerere` to save time resolving conflicts in + a later “real,” permanent merge. + +* You can use `git checkout -p` to build new, tidy commits out of a branch + laden with “wip” commits: + + git fetch + git checkout $(git merge-base origin/master foo) -b foo-cleaner-history + git checkout -p foo -- paths/to/files + # pick out changes from the presented patch that form a coherent commit + # repeat 'git checkout -p foo --' steps for related files to build up + # the new commit + git commit + # repeat 'git checkout -p foo --' and 'git commit' steps until no diffs remain + + * Gotcha: `git checkout -p` will do nothing for files that are being + created. Use `git checkout`, instead, and edit the file if necessary. + Thanks, Git. + * Gotcha: The new, clean branch must diverge from its upstream branch + (`origin/master`, in the example above) at exactly the same point, or + the diffs presented by `git checkout -p foo` will include chunks that + revert changes on the upstream branch since the “dirty” branch was + created. The easiest way to find this point is with `git merge-base`. + +## Useful Resources + +That is, resoures that can help you solve problems or understand things, not +resources that reiterate the man pages for you. + +* Sitaram Chamarty's [git concepts + simplified](http://sitaramc.github.com/gcs/) +* Tv's [Git for Computer + Scientists](http://eagain.net/articles/git-for-computer-scientists) |