CODEWITHSUNDEEP
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doug
doug

Reputation: 1819

How can I diff changed files versus previous versions after a pull?

When I run "git pull", I often want to know what changed between the last version of a file and the new one. Say I want to know what someone else committed to a particular file.

How is that done?

I'm assuming it's "git diff" with some parameters for commit x versus commit y, but I can't seem to get the syntax. I also find "git log" confusing a bit and am not sure where to get the commit ID of my latest version of the file versus the new one.

Upvotes: 141

Views: 137268

Answers (4)

Henry S.
Henry S.

Reputation: 548

If you want to see the difference only on a file, you can try the commands to compare it with the last version.

git diff HEAD@{1} filename

git diff HEAD@{1} -- path/filename

Note: -- is needed if your file is not in the current directory. Otherwise, you may get following error.

fatal: ambiguous argument 'path/filename': unknown revision or path not in the working tree. Use '--' to separate paths from revisions, like this: 'git [...] -- [...]'

Upvotes: 2

cadizm
cadizm

Reputation: 946

I like to use:

git diff HEAD^

Or if I only want to diff a specific file:

git diff HEAD^ -- /foo/bar/baz.txt

Upvotes: 72

CB Bailey
CB Bailey

Reputation: 793199

If you do a straight git pull then you will either be 'fast-forwarded' or merge an unknown number of commits from the remote repository. This happens as one action though, so the last commit that you were at immediately before the pull will be the last entry in the reflog and can be accessed as HEAD@{1}. This means that you can do:

git diff HEAD@{1}

However, I would strongly recommend that if this is something you find yourself doing a lot then you should consider just doing a git fetch and examining the fetched branch before manually merging or rebasing onto it. E.g. if you're on master and were going to pull in origin/master:

git fetch

git log HEAD..origin/master

 # looks good, lets merge

git merge origin/master

Upvotes: 15

Cascabel
Cascabel

Reputation: 497652

There are all kinds of wonderful ways to specify commits - see the specifying revisions section of man git-rev-parse for more details. In this case, you probably want:

git diff HEAD@{1}

The @{1} means "the previous position of the ref I've specified", so that evaluates to what you had checked out previously - just before the pull. You can tack HEAD on the end there if you also have some changes in your work tree and you don't want to see the diffs for them.

I'm not sure what you're asking for with "the commit ID of my latest version of the file" - the commit "ID" (SHA1 hash) is that 40-character hex right at the top of every entry in the output of git log. It's the hash for the entire commit, not for a given file. You don't really ever need more - if you want to diff just one file across the pull, do

git diff HEAD@{1} filename

This is a general thing - if you want to know about the state of a file in a given commit, you specify the commit and the file, not an ID/hash specific to the file.

Upvotes: 180

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