Say that you want to see what has changed between two different commits. You can do
git diff sha1..sha2
The above command will give you all the differences between sha1 (exclusive) to sha2 (inclusive). However, textual diffs can be hard to understand sometimes, so how would you specify a visual diff tool? The easiest way would be to specify the name of the visual diff tool directly to git difftool i.e.
git difftool -t path_to_tool sha1..sha2
If you find yourself using a particular visual diff tool pretty often, then you
should add it to your global git config file, shown with a hypothetical tool
called awesometool:
git config --global diff.tool awesometool
git config --global difftool.awesometool.cmd "path/to/awesometool \$LOCAL \$REMOTE"
# The following gets rid of having to hit enter when you run git difftool
git config --global difftool.prompt false
which will create the following entries in your global .gitconfig
[diff]
tool = awesometool
[difftool "awesometool"]
cmd = path/to/awesometool \"$LOCAL\" \"$REMOTE\"
[difftool]
prompt = false
Popular visual diff tools are vimdiff, kdiff3, meld, etc. You can specify several programs (not just a single one) that you use frequently through the global git config.
git difftool sha1..sha2
Once you add your visual diff tool to git configurations, you can simply invoke
git difftool as follows.
References