How to view file diff in git before commit

If you want to see what you haven't git added yet:

git diff myfile.txt

or if you want to see already added changes

git diff --cached myfile.txt

git diff HEAD file

will show you changes you added to your worktree from the last commit. All the changes (staged or not staged) will be shown.

To check for local differences:

git diff myfile.txt

or you can use a diff tool (in case you'd like to revert some changes):

git difftool myfile.txt

^{To use git difftool more efficiently, install and use your favourite GUI tool such as Meld, DiffMerge or OpenDiff.}

Note: You can also use . (instead of filename) to see current dir changes.

In order to check changes per each line, use: git blame which will display which line was commited in which commit.

To view the actual file before the commit (where master is your branch), run:

git show master:path/my_file

Another technique to consider if you want to compare a file to the last commit which is more pedantic:

git diff master myfile.txt

The advantage with this technique is you can also compare to the penultimate commit with:

git diff master^ myfile.txt

and the one before that:

git diff master^^ myfile.txt

Also you can substitute '~' for the caret '^' character and 'you branch name' for 'master' if you are not on the master branch.

Did you try -v (or --verbose) option for git commit? It adds the diff of the commit in the message editor.