How to diff one file to an arbitrary version in Git?

Question

How can I diff a file, say pom.xml, from the master branch to an arbitrary older version in Git?

Answer 1

To see what was changed in a file in the last commit:

git diff HEAD~1 path/to/file

You can change the number (~1) to the n-th commit which you want to diff with.

Answer 2

Generic Syntax :

$git diff oldCommit..newCommit -- **FileName.xml > ~/diff.txt

for all files named "FileName.xml" anywhere in your repo.

Notice the space between "--" and "**"

Answer for your question:

$git checkout master
$git diff oldCommit..HEAD -- **pom.xml 
or
$git diff oldCommit..HEAD -- relative/path/to/pom.xml 

as always with git, you can use a tag/sha1/"HEAD^" to id a commit.

Tested with git 1.9.1 on Ubuntu.

Answer 3

git diff <revision> <path>

For example:

git diff b0d14a4 foobar.txt

Answer 4

If neither commit is your HEAD then bash's brace expansion proves really useful, especially if your filenames are long, the example above:

git diff master~20:pom.xml master:pom.xml

Would become

git diff {master~20,master}:pom.xml

More on Brace expansion with bash.

Answer 5

If you want to see the difference between the last commit of a single file you can do:

git log -p -1 filename

This will give you the diff of the file in git, is not comparing your local file.

Answer 6

For people interested in doing the same from GitHub, see comparing commits across time.