Git tips

Tips for myself for git

git add

• git add -N <file> adds a file, but does not stage the changes in the file to the index. This allows you to split the changes to this file into atomic commits

• git add -A adds and removed all added and deleted files from the index and stages all changes. It is not equivalent to hg addremove because it stages all changes to the index

git commit

• git commit -a stages all changes to tracked files and removes any deleted files from the index. This is equivalent to git add -u; git commit

• git commit --amend appends the current staged edits to the previous commit, creating a new commit. Add --no-edit to keep the same commit message

git checkout

• git checkout <rev> -- <file>, leave <rev> empty if you want to update to the current index, or use HEAD to update to the local repository

git diff

diff --git a/importantFile b/importantFile
new file mode 100644
index 0000000..3d44acd
--- /dev/null
+++ b/importantFile
@@ -0,0 +1,2 @@
+important stuff
+crazy change

• Notice the 0000000..3d44acd is not the commit hash, but the file hash

git log

• git log --graph --decorate --oneline $(git rev-list -g --all) shows all the branches, including unnamed ones and stashes

• git log -p shows detailed commits

git push

• git push --all origin pushes a new branch (don’t necessarily need origin - only if you have multiple upstreams)

• git push --set-upstream origin thirdbranch pushes the current branch and sets the remote as the upstream remote repository

• git push origin master will push the master branch to origin even if you are in a detached HEAD state

git rebase

The standard workflow is as follows - we start with HEAD on the master branch tip. Then:

git checkout -b feature master # create a branch at the same point as the master branch 
# add feature
git commit -am "Started developing a new feature" 
# go back to master to make an important change - do this in another branch
git checkout -b quickfix master 
# fix critical bug
git commit -am "Fixed bug"
git checkout master
git merge quickfix
git branch -d quickfix

Now, we have a fork. We could do a straight merge of the feature, or we could use a rebase - this retains linear history. It must be certain that no one else has pulled the feature branch, as this will be removed and re-written by a set of entirely different commits

git checkout feature
git rebase master

At this point, the history looks like

* cc2bfa3 (HEAD, feature) Started developing a new feature
* b000ff1 (master) Fixed bug

Now, we have to do a fast forward merge (this is an easy merge, it’s just moving the branch head location forward a few commits)

git checkout master
git merge feature # Deal with potential merge conflicts in the standard way
git branch -d feature

And we have fully integrated the feature into the main branch.

git rebase -i

Still need to cover this

git reset

• git reset unstages all files, allowing you to recreate the commit snapshot from scratch, but it leaves the working directory unchanged. Adding --hard destroys all changes in the working directory, so there are no differences to be unstaged. It resets the working directory to the original commit