How do I copy a version of a single file from one Git branch to another?

I would use git restore (available since Git 2.23):

git restore --source otherbranch path/to/myfile.txt

Why is this better than other options?

• by default git restore modifies files only in the working directory

git checkout otherbranch -- path/to/myfile.txt copies the file to the working directory (your files on disk) but also to the staging area. It has the same effect as if you copied the file manually and executed git add on it. git restore by default changes only the working directory.

To get the same result as for git checkout otherbranch -- path/to/myfile.txt you can write git restore --source otherbranch --staged --worktree path/to/myfile.txt

• by default git restore deletes files from the working directory when they are absent in the other branch

git restore can be used to restore the whole folder with git restore --source otherbranch path/to/dir. You can do a similar operation with git checkout but git restore by default will delete files that are absent in otherbranch. To get git checkout behaviour use --overlay option.

For example, if there are fewer files on otherbranch than in the current working directory (and these files are tracked) without --overlay option git restore will delete them. But this is a good default behaviour because you most likely want the state of the directory to be "the same as otherbranch", not "the same as otherbranch but with additional files from my current branch".

To really get the same result as for git checkout otherbranch -- path/to/dir you can write git restore --source otherbranch --staged --worktree --overlay path/to/dir

• git restore doesn't use shell redirection to create file (Powershell only problem)

git show otherbranch:path/to/myfile.txt > path/to/myfile.txt uses standard shell redirection. If you use PowerShell then there might be problem with text encoding or could result in a corrupt file if it's binary (update: fixed in PowerShell 7.4). With git restore changing files is done all by the git executable.

I ended up at this question on a similar search. In my case I was looking to extract a file from another branch into current working directory that was different from the file's original location. Answer:

git show TREEISH:path/to/file > path/to/local/file

Use the checkout command:

  git diff --stat "$branch"
  git checkout --merge "$branch" "$file"
  git diff --stat "$branch"

1. Ensure you're in branch where you need a copy of the file.

   For example: I want sub branch file in master, so you need to checkout or should be in master git checkout master

2. Now check out the specific file alone you want from the sub branch into master,

    git checkout sub_branch file_path/my_file.ext
   

   Here sub_branch means where you have that file followed by filename you need to copy.

Following madlep's answer, you can also just copy one directory from another branch with the directory blob.

git checkout other-branch app/**

As to the OP's question if you've only changed one file in there, this will work fine.

Sorry, no one mentioned that before restoring a file you really want to preview local changes in relation to that branch, so:

git diff <other-branch-name> -- <filename>

Then when you're accepting a lost (overwritting), you can follow by:

git restore --source <other-branch-name> <filename>
or
git checkout <other-branch-name> <filename>

Please note that in the accepted answer, the first option stages the entire file from the other branch (like git add ... had been performed), and that the second option just results in copying the file, but doesn't stage the changes (as if you had just edited the file manually and had outstanding differences).

Git copy file from another branch without staging it

Changes staged (e.g. git add filename):

$ git checkout directory/somefile.php feature-B

$ git status
On branch feature-A
Your branch is up-to-date with 'origin/feature-A'.
Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)

        modified:   directory/somefile.php

Changes outstanding (not staged or committed):

$ git show feature-B:directory/somefile.php > directory/somefile.php

$ git status
On branch feature-A
Your branch is up-to-date with 'origin/feature-A'.
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

        modified:   directory/somefile.php

no changes added to commit (use "git add" and/or "git commit -a")

All the git based answers are confusing and works on certain assumptions. I would rather present a more simplistic approach which works for files or folders.

git checkout other_branch

# Copy a single file
cp path/to/file /tmp/

# Copy a folder
cp -r path/to/folder /tmp/

git checkout my_branch

# Copy file/folder from /tmp dir to wherever you like.

If it ain't broken etc...