How do I show uncommitted changes in Git?

I STFW'ed, and these commands are not working:

teyan@TEYAN-THINK MINGW64 /d/nano/repos/PSTools/psservice (teyan/psservice)
$ git status
On branch teyan/psservice
Your branch is up-to-date with 'origin/teyan/psservice'.
Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)
    modified:   psservice.c
    modified:   psservice.vcxproj.filters
teyan@TEYAN-THINK MINGW64 /d/nano/repos/PSTools/psservice (teyan/psservice)
$ git diff
teyan@TEYAN-THINK MINGW64 /d/nano/repos/PSTools/psservice (teyan/psservice)
$ git diff master
fatal: ambiguous argument ‘master’: unknown revision or path not in the working tree.
Use ‘–’ to separate paths from revisions, like this:
‘git <command> [<revision>…] – [<file>…]’

How to show uncommitted changes in Git

The command you are looking for is git diff.

git diff - Show changes between commits, commit and working tree, etc

Here are some of the options it expose which you can use

git diff (no parameters)
Print out differences between your working directory and the index.

git diff --cached:
Print out differences between the index and HEAD (current commit).

git diff HEAD:
Print out differences between your working directory and the HEAD.

git diff --name-only
Show only names of changed files.

git diff --name-status
Show only names and status of changed files.

git diff --color-words
Word by word diff instead of line by line.

Here is a sample of the output for git diff --color-words: