Mandatory arguments to long options are mandatory for short options too.
-o, --output=FILE operate interactively, sending output to FILE
-i, --ignore-case consider upper- and lower-case to be the same
-E, --ignore-tab-expansion ignore changes due to tab expansion
-Z, --ignore-trailing-space ignore white space at line end
-b, --ignore-space-change ignore changes in the amount of white space
-W, --ignore-all-space ignore all white space
-B, --ignore-blank-lines ignore changes whose lines are all blank
-I, --ignore-matching-lines=RE ignore changes all whose lines match RE
--strip-trailing-cr strip trailing carriage return on input
-a, --text treat all files as text
-w, --width=NUM output at most NUM (default 130) print columns
-l, --left-column output only the left column of common lines
-s, --suppress-common-lines do not output common lines
-t, --expand-tabs expand tabs to spaces in output
--tabsize=NUM tab stops at every NUM (default 8) print columns
-d, --minimal try hard to find a smaller set of changes
-H, --speed-large-files assume large files, many scattered small changes
--diff-program=PROGRAM use PROGRAM to compare files
--help display this help and exit
-v, --version output version information and exit
If a FILE is '-', read standard input. Exit status is 0 if inputs are the same, 1 if different, 2 if trouble.
GNU diffutils home page: <https://www.gnu.org/software/diffutils/>
General help using GNU software: <https://www.gnu.org/gethelp/>
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.
The full documentation for GNU is maintained as a Texinfo manual. If the info and GNU programs are properly installed at your site, the command
info GNUshould give you access to the complete manual.