What does the caret (^) character mean in Git?

Asked 23/12, 2009 at 23:53 Answered 30/5, 2022 at 8:55

164

I saw an answer to a question here that helps restore a deleted file in git.

The solution was

git checkout <deleting_commit>^ -- <deleted_file_path>

What does the caret character (^) do? I’ve seen it elsewhere doing very useful things in git. It’s magical. Someone please spoil it for me and tell me what it does?

Mush answered 23/12, 2009 at 23:53 Comment(2)

FYI on windows: ^ doesn't work as expected in DOS shell. Use git bash shell and then it works. – Nahama 27/9, 2011 at 0:59

That didn't even occur to me when I've attempted to use it (guessing on what it means). The caret (^) is the escape character in cmd.exe. Every time I've tried to use it to see if it would be helpful I was actually passing nothing, which explains why the results were never different. >_> Stupid cmd.exe. You can escape it by doubling it or quoting it: git log master^^ or git log "master^" – Lorrianelorrie 24/7, 2012 at 20:24

180

HEAD^ means the first parent of the tip of the current branch.

Remember that git commits can have more than one parent. HEAD^ is short for HEAD^1, and you can also address HEAD^2 and so on as appropriate.

You can get to parents of any commit, not just HEAD. You can also move back through generations: for example, master~2 means the grandparent of the tip of the master branch, favoring the first parent in cases of ambiguity. These specifiers can be chained arbitrarily , e.g., topic~3^2. See related answer to What’s the difference between HEAD^ and HEAD~ in Git?

For the full details, see the “Specifying Revisions” section of git rev-parse --help.

Cathey answered 24/12, 2009 at 0:14 Comment(2)

But then, on linear history, why does HEAD^^^ return the third older commit i.e. it is equivalent to HEAD~~~? – Stenographer 10/5, 2014 at 12:37

@Stenographer For linear history, yes. – Cathey 10/5, 2014 at 16:57

It means "parent of". So HEAD^ means "the parent of the current HEAD". You can even chain them together: HEAD^^ means "the parent of the parent of the current HEAD" (i.e., the grandparent of the current HEAD), HEAD^^^ means "the parent of the parent of the parent of the current HEAD", and so forth.

Simplistic answered 23/12, 2009 at 23:56 Comment(3)

This answer is not right for merge commits. If HEAD is following a merge commit, then HEAD^ means the first parent of HEAD, and HEAD^^ (or HEAD^2) means the second parent of HEAD. In a merge commit, the second parent of HEAD is not the same thing as the parent of the parent of HEAD. See Ancestry References in the Git manual. – Fable 7/10, 2022 at 23:5

@bhagerty: That is wrong. While HEAD^2 does indeed indicate the second parent of HEAD, HEAD^2 and HEAD^^ are not synonymous. Multiple carets do refer to commits in relation to the first parent, so just as HEAD^^ refers in general to the grandparent of HEAD, HEAD^^ the grandparent of parent of the first commit of HEAD when HEAD is a merge commit; likewise, HEAD^2^ is the parent of the second parent. – Simplistic 9/10, 2022 at 3:23

Thanks, @mipadi. I assume you are correct, though the documentation doesn't come close to making this clear. As far as I can tell, HEAD~~ and HEAD~2 are synonymous, so by analogy, I expected the number operator to work similarly with the caret. From what you are saying, it does not. That is unfortunate. – Fable 15/10, 2022 at 3:24

The ^ (caret) can also be used when specifying ranges.

To exclude commits reachable from a commit, a prefix ^ notation is used. E.g. ^r1 r2 means commits reachable from r2 but exclude the ones reachable from r1.

<rev>

Include commits that are reachable from (i.e. ancestors of) .

^<rev>

Exclude commits that are reachable from (i.e. ancestors of) .

Galeiform answered 4/3, 2016 at 23:32 Comment(1)

yep, this was exactly what I was searching for. – Conventioner 30/8, 2021 at 17:19

Here's a visual explanation. Suppose you have a history like so:

                      master  
  ... <- B <- C <- D
             /
... <- E <- F
              feature

When feature was merged into master, C was created with two ancestors. Git assigns these ancestors numbers. The mainline ancestor B is assigned 1 and the feature ancestor F is assigned 2.

Thus C^1 refers to B and C^2 refers to F. C^ is an alias for C^1.

You would only ever use <rev>^3. if you had performed a merge of three branches.

Gropius answered 20/1, 2017 at 22:37 Comment(3)

is that actually legal? can a merge commit contain three parents? – Gensmer 8/2, 2021 at 15:41

A merge commit can have N parents. The only distinction between a regular commit and a merge is the number of parents. – Gropius 8/2, 2021 at 17:49

After going through this comment, reading stackoverflow.com/questions/2221658/… gives more clarity – Discouragement 28/11, 2022 at 7:8

The caret refers to the parent of a particular commit. E.g. HEAD^ refers to the parent of the current HEAD commmit. (also, HEAD^^ refers to the grandparent).

Biddick answered 23/12, 2009 at 23:55 Comment(0)

OP: What does the caret (^) character mean in Git?

The ^ (Caret) and ~ (Tilde) selectors

The difference between HEAD^ (Caret) and HEAD~ (Tilde) is how they traverse history backwards from a specified starting point, in this particular case HEAD.

Tilde ~

<rev>~[<n>] = select <n>th generation ancestor, following only first* parents

Caret ^

<rev>^[<n>] = select <n>th parent of first generation ancestors

*First parent is always the left hand side of the merge, e.g. the commit on the branch that got merged into.

Joining ~ and ^ together

As seen in the illustration below the two selectors ~ and ^ can be used in combination. Also note that instead of using HEAD as a starting point, any regular reference can be used such as a branch, tag or even a commit hash.

Further more, depending on what ancestor is intended to be selected ^ and ~ can be used interchangeably as seen below in the table.

Source: A thorough rundown can be found in this blog post on the subject.

Polygyny answered 30/5, 2022 at 8:55 Comment(2)

This is a near-perfect explanation and diagram. The only minor comment I have relates to the letters in the diagram. I think it would be easier to understand if the letters went backwards in the alphabet. The way you have it now, the flow of the letters is contrary to the flow of time, which is counterintuitive. It's clear from your arrow of time that C came before B came before A in time. But this is not how we expect the alphabet to work. – Fable 8/10, 2022 at 3:12

Thanks for your feedback @Fable ! And great suggestion, I'll definitely look into making the change. Indeed, it's a bit counter intuitive. – Coaster 9/10, 2022 at 8:22

The carat represents a commit offset (parent). So for instance, HEAD^ means "one commit from HEAD" and HEAD^^^ means "three commits from HEAD".

Mediant answered 23/12, 2009 at 23:56 Comment(0)

The (^) gets the parent source of the command i.e. HEAD^ will get the parent of HEAD.

Joanne answered 23/12, 2009 at 23:57 Comment(0)

Greg Bacon gave a great link, but it's pretty dense. The Git introductory docs online also introduce revision and range specifiers:

https://git-scm.com/book/en/v2/Git-Tools-Revision-Selection

Jesuitism answered 30/11, 2012 at 1:53 Comment(1)

This link might be closer to the location intended. git-scm.com/book/en/v2/… – Beall 7/11, 2014 at 2:12

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The ^ (Caret) and ~ (Tilde) selectors

Tilde ~

Caret ^

Joining ~ and ^ together

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