Differences

This shows you the differences between two versions of the page.

--- git [2026/06/14 02:08] – [merge vs rebase] jhagstrand
+++ git [2026/06/16 00:13] (current) – [diff] jhagstrand
@@ Line 29: / Line 29: @@
   * HEAD - ?
   * detached head - ?
+  * tree-ish ?
   * commit-ish
   * SHA-1 value
@@ Line 205: / Line 206: @@
+Starting situation\\
+There are commits on the feature branch.\\
+What about the master branch?  There are three possibilities:
+  * no commits on the master
+  * commits on the master but no conflicts
+  * commits on the master with conflicts
+Desired outcome.\\
+The master branch is up-to-date, and the feature branch is gone.\\
+But how will the log look?  There are three possibilities:
+  * Linear. The feature branch commits are all present in the master branch, as if the branch never existed.
+  * Indented. The feature branch commits have are all present, but indented under a merge commit, so you can see there must have been a branch there at one time.
+  * Collapsed. The feature branch commits are all gone, replaced by a single merge commit with a hand-written merge message that summarizes all the commits of the branch.
+==== Squash Merge ====
+The --squash option, the merge command does not really do a merge.  Instead it copies all of the changed files from the feature branch to the master branch.  So now you do a single commit on the master branch, write a commit message summarizing all the individual commits made on the feature branch.
+This is one of the ways to collapse a developer's many chaotic commits into a single nice-looking well-thought-out commit.
+  # Make sure you're on the branch you want to merge into
+  git checkout master
+  # merge the feature branch with --squash option
+  # this stages all the file changes into the master branch
+  git merge --squash feature
+  # ask for status now and you'll see all the changes ready for commit
+  git status
+  # now commit
+  git commit -m "feat: add feature command"
+  # delete the feature branch
+  git branch -D feature
+  # for fun do a log all between these commands to see what's going on
+  git log --all --oneline -15 --graph --decorate
+==== Log ====
+git commit adds an entry to the log.
+How to fuck with the log.
+  * git merge
+  * git rebase
+  * git reset
+git reset --hard HEAD^
+Effectively deletes the most recent commit.  Equivalent to aider /undo.
@@ Line 222: / Line 273: @@
 ====diff====
-Use diff to find the differences between two branches or between two files.\\
+Use diff to find the differences between two commits.\\
-Note that there is a big difference between .. and ... between the two commit designations.\\
-Also the two hyphens -- can go before or after the filename and that alters the output.\\
-  git diff master...featurebranch  # compare two branches
+  git diff 1bde095 b0ba90d   # compare two commits
+  git diff master sidebar    # compare two branches
-  git diff 1bde095..b0ba90d -- html/js/hud.js  # compare two different commits of a file
+  git diff master sidebar hud.js  # compare two versions of a file
 By default diff compares all of the currently modified files.
@@ Line 238: / Line 287: @@
 Additional options.
+  git diff master sidebar --stat   # show filenames and counts only
   git diff -U0	# do not display context
-  git diff -w	# ignore whitespace
-  git diff -w --word-diff-regex=[^[:space:]]	# ignore whitespace additional
+Whitespace.\\
 In .gitconfig, add
 [core] whitespace = -trailing-space,-indent-with-non-tab,-tab-in-indent
+  git diff -w	# ignore whitespace
+  git diff -w --word-diff-regex=[^[:space:]]	# ignore whitespace additional
-====log====
+Dots.\\
+If both master and sidebar have changed, and you want to see only differences in sidebar, use three dots.  (This is a shortcut to naming the commit specifically.)\\
+Warning! Two dots vs three dots makes a difference, and the difference is reversed in git diff vs git log.\\
-git log
+  git diff master sidebar poker.js  # compare changes from latest master to latest sidebar
+  git diff master..sidebar poker.js  # same as no dots
+  git diff master...sidebar poker.js  # not latest master but master when sidebar branched
-git log --oneline -10
+Double hyphens.\\
+I don't know why this is used.\\
-git log --oneline --graph # shows a hierarchy of branches
+  git diff master sidebar hud.js
+  git diff master sidebar -- hud.js
+  git diff master sidebar hud.js --
+====log====
+  git log
+  git log master   # show log for one branch
+  git log --oneline -10  # default to currently checked out branch
+  git log --all --oneline --graph --decorate  # all branches, graph hierarchy
+  git log --oneline -10     # topmost n lines
+  git log --all --pretty=fuller
 ==== interactive rebase ====