How do I get a particular (older) version of a file from git repository without wiping out later versions?

Question

I should think that getting a previous version is one of source control's premier features, and should be simple, yet it seems like a treasure hunt finding git solution.

I came across stackoverflow question How can I check out a particular version of one file in Git? . To paraphrase the key thing:

git checkout <commit hash from git log output>

As I expected it to happen, the file in the working directory was replaced/updated with the requested older version, but I lost the later versions in the repository, got a message like "... detached head...".

Any guiding principles here would be appreciated. Thanks.

Answer 1

If you have a special commit like abc123456 and in that commit the file was good, you just need to ...

git checkout abc123456 path/to/file

with this command you will find in stage that version of the file.

You can also use branches:

git checkout old-branch-name path/to/file

Answer 2

When you just use git checkout <somehash> , then you will get into a detached HEAD. This happens because git checkout by default just switches branches, and specifying a commit instead of a branch gets you into a “branchless mode” (that's what detached HEAD means).

If you want to get a single file from a different version, you also need to specify the path, ie git checkout <somehash> -- path/to/file . This will keep everything as it is and just replace the file at path/to/file with its version from <somehash> .

So this does overwrite the file. If you want to keep the current version as well, you should rename it first. Otherwise, you can also use a special syntax of git show for this

git show <somehash>:path/to/file > new_filename.ext

This will essentially get the contents of the file from <somehash> and print it, so if you pipe it to file, you can extract a file from a different version into a different filename.