I have some markdown files but I can't git diff them.
No result at the command line and not supported in
gitg (visual git)
Is that possible with the files as they are, without converting them to something else?
It should work fine; markdown files are plaintext files, so
git diff is perfect.
This could be one of a few possible things:
git add -p *.md)
git status say? If it doesn't contain a few lines that say something like "modified: something.md" or "new file: something.md" then you're not going to get a diff.
EDIT: These files are actually in a git repo right? If not, just use Unix's normal diff utility (
man diff for more info).