Add gitrevisions

git-revisions.md

@@ -0,0 +1,53 @@
+---
+title: Git revisions
+---
+
+### Single commits
+
+- commits:
+  - `dae68e1` (sha1)
+
+- refs:
+  - `HEAD` (ref)
+  - `master` (branch)
+  - `v1.0.0` (tag)
+  - `origin/master` (aka, *refs/remotes/origin/master*)
+  - `heads/master`
+  - `refs/heads/master`
+
+- search back:
+  - `master@{yesterday}`
+  - `master@{2}` (2nd prior value)
+  - `master@{push}` (where *master* would push to)
+  - `master^` (parent)
+  - `master^2` (2nd parent, eg, what it merged)
+  - `master~5` (5 parents back)
+  - `master^0` (this commit; disambiguates from tags)
+  - `v0.99.8^{tag}` (can be *commit*, *tag*, *tree*, *object*)
+  - `v0.99.8^{}` (defaults to *{tag}*)
+  - `:/fix bug` (searches commit messages)
+- other:
+  - `HEAD:README`
+  - `0:README` (0 to 3)
+
+### Ranges
+
+- `master` (reachable parents from master)
+- `^master` (exclude reachable parents from master)
+- `master..fix` (reachable from *fix* but not *master*)
+- `master...fix` (reachable from *fix* and *master*, but not both)
+- `HEAD^@` (parents of *HEAD*)
+- `HEAD^!` (*HEAD*, then excluding parents's ancestors)
+
+### Ranges illustration
+
+```
+ F   - master
+ E C - fix
+ D B
+ |-'
+ A
+
+master..fix   = BC
+master...fix  = BC and FED
+```