git diff can show you the difference between two commits:

git diff mybranch master -- myfile.cs

Or, equivalently:

git diff mybranch..master -- myfile.cs

Using the latter syntax, if either side is HEAD it may be omitted (e.g. master.. compares master to HEAD).

You may also be interested in mybranch...master (from git diff docs):

This form is to view the changes on the branch containing and up to the second <commit>, starting at a common ancestor of both <commit>. git diff A...B is equivalent to git diff $(git-merge-base A B) B.

In other words, this will give a diff of changes in master since it diverged from mybranch (but without new changes since then in mybranch).


In all cases, the -- separator before the file name indicates the end of command line flags. This is optional unless Git will get confused if the argument refers to a commit or a file, but including it is not a bad habit to get into. See https://stackoverflow.com/a/13321491/54249 for a few examples.


The same arguments can be passed to git difftool if you have one configured.