Unable to diff files in two separate branches in Git

Question

I have FileA in branchA and FileB in branchB.

The problem is that I can access only one file at time. I would like to be able to compare the files by FileMerge or mel

Answer 1

git supports branch names as part of the repository paths. Eg if you have the following files in your repository, README only on master, and UNREADME only on branch:

master:README

branch:UNREADME

You can diff them via git with:

git diff branch:UNREADME master:README

You can get a repository artifact to standard output with git show:

git show branch1:UNREADME

So if your external diff utility can take 2 files on the bash prompt, you can diff them with something like:

diff-command <(git show branch1:UNREADME) <(git show master:README)

Where the <(...) bash syntax takes the output of the enclosed command, runs it in a pipe and places the file path of the pipe on the command line.