Add Count Number Of Commits On A Branch as a git TIL

git/count-number-of-commits-on-a-branch.md

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+# Count Number Of Commits On A Branch
+
+The `git rev-list` command will show all commits that fit the given revision
+criteria. By adding in the `--count` flag, we get a count of the number of
+commits that would have been displayed. Knowing this, we can get the count of
+commits for the current branch like so:
+
+```bash
+$ git rev-list --count HEAD
+4
+```
+
+This finds and counts commits from `HEAD` (usually the top of the current
+branch) all the back in reverse chronological order to the beginning of the
+branch (typically the beginning of the repository). This works exactly as
+expected for a the `main` branch.
+
+What about when we are on a feature branch though?
+
+Let's say we've branched off `main` and made a few commits. And now we want the
+count.
+
+```bash
+$ git rev-list --count HEAD
+7
+```
+
+Unfortunately, that is counting up the commits on the feature branch but it
+keeps counting all the way back to the beginning of the repo.
+
+If we want a count of just the commits on the current branch, then we can
+specify a range: from whatever `main` was when we branched to the `HEAD` of
+this branch.
+
+```bash
+$ git rev-list --count HEAD
+3
+```
+
+This is the same as saying, I want all commits on `HEAD`, but exclude (`^`) the
+commits on `main`:
+
+```bash
+git rev-list --count HEAD ^main
+3
+```
+
+See `man git-rev-list` for more details.