Convenient diff command usage notes
Compare files
diff {File A} {File B}
Add! To the difference and compare
diff -c {File A} {File B}
Compare case-insensitive
diff -i {File A} {File B}
If the files are the same, display as the same
diff -s {File A} {File B}
If the contents of the file are different, display as different without displaying the contents
diff -q {File A} {File B}
Compare files, ignoring whitespace
diff -w {File A} {File B}
Compare by directory
diff -r {Directory A} {Directory B}
Compare by directory without displaying the contents
diff -rq {Directory A} {Directory B}