Way to see with git if a file has been changed?

Question

I have a script that detects changes in file.txt and if changes are present, commits and pushes them. I thought of doing this by issueing a git diff to see whether the file has changed.

Now, there are 2 cases I could think of:

• if the file is new, it is untracked yet; it has to be staged in order to successfully do a git diff --name-only --cached to see that the file should be pushed;
• if the file is not new, it has to be added in order to successfully do a git diff --name-only to see that the file should be pushed.

My questions are:

• how can I combine the above two cases (and possibly more, if I missed some) into a simple condition? Or, how do I treat differently whether the file has been created or it is new?
• is git add <file> safe any way it is being used? Meaning, if the file is tracked/untracked, it has been staged/has not been staged yet etc.

Answer 1

Just use git status. You can use the --porcelain parameter to get a concise machine-readable output which you can easily parse.

Also, you can always just use git add filename (or git add . for everything in the current directory) to stage files. If they have not been modified, then nothing will happen, and if there are changes, those changes will be staged. And similarly, if it hasn’t been tracked before, it will be tracked and staged then. You could also use git add -u to just update all already-staged files, staging any changes (even file deletions).