What's the difference between "git reset" and "git checkout"?
I've always thought of git reset and git checkout as the same, in the sense that both bring the project back to a specific commit. However, I feel they can't be exactly the same, as that would be redundant. What is the actual difference between the two? I'm a bit confused, as the svn only has svn co to revert the commit.
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The following diagram explains the difference, albeit in an either possibly oversimplified or incorrect manner. What do you think? Is it wrong or overly simplified?
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VonC and Charles explained the differences between git reset and git checkout really well. My current understanding is that git reset reverts all of the changes back to a specific commit, whereas git checkout more or less prepares for a branch. I found the following two diagrams quite useful in coming to this understanding:
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From http://think-like-a-git.net/sections/rebase-from-the-ground-up/using-git-cherry-pick-to-simulate-git-rebase.html, checkout and reset can emulate the rebase.
git checkout bar
git reset --hard newbar
git branch -d newbar
git reset is specifically about updating the index , moving the HEAD. git checkout is about updating the working tree (to the index or the specified tree). It will update the HEAD only if you checkout a branch (if not, you end up with a detached HEAD). By comparison, since svn has no index, only a working tree, svn checkout will copy a given revision on a separate directory.
The closer equivalent for git checkout would:
svn update (if you are in the same branch, meaning the same SVN URL) svn switch (if you checkout for instance the same branch, but from another SVN repo URL) All those three working tree modifications ( svn checkout , update , switch ) have only one command in git: git checkout .
But since git has also the notion of index (that "staging area" between the repo and the working tree), you also have git reset .
Thinkeye mentions in the comments the article "Reset Demystified ".
For instance, if we have two branches, ' master ' and ' develop ' pointing at different commits, and we're currently on ' develop ' (so HEAD points to it) and we run git reset master , ' develop ' itself will now point to the same commit that ' master ' does.
On the other hand, if we instead run git checkout master , ' develop ' will not move, HEAD itself will. HEAD will now point to ' master '.
So, in both cases we're moving HEAD to point to commit A , but how we do so is very different. reset will move the branch HEAD points to, checkout moves HEAD itself to point to another branch.
In their simplest form, reset resets the index without touching the working tree, while checkout changes the working tree without touching the index.
Resets the index to match HEAD , working tree left alone:
git reset
Conceptually, this checks out the index into the working tree. To get it to actually do anything you would have to use -f to force it to overwrite any local changes. This is a safety feature to make sure that the "no argument" form isn't destructive:
git checkout
Once you start adding parameters it is true that there is some overlap.
checkout is usually used with a branch, tag or commit. In this case it will reset HEAD and the index to the given commit as well as performing the checkout of the index into the working tree.
Also, if you supply --hard to reset you can ask reset to overwrite the working tree as well as resetting the index.
If you current have a branch checked out out there is a crucial different between reset and checkout when you supply an alternative branch or commit. reset will change the current branch to point at the selected commit whereas checkout will leave the current branch alone but will checkout the supplied branch or commit instead.
Other forms of reset and commit involve supplying paths.
If you supply paths to reset you cannot supply --hard and reset will only change the index version of the supplied paths to the version in the supplied commit (or HEAD if you don't specify a commit).
If you supply paths to checkout , like reset it will update the index version of the supplied paths to match the supplied commit (or HEAD ) but it will always checkout the index version of the supplied paths into the working tree.
One simple use case when reverting change:
1. Use reset if you want to undo staging of a modified file.
2. Use checkout if you want to discard changes to unstaged file/s.
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