Problem: xxd: no color support
Solution: Add color support using xxd -R
Add some basic color support for xxd
The hex-value and value are both colored with the same color depending
on the hex-value, e.g.:
0x00 = white
0xff = blue
printable = green
non-printable = red
tabs and linebreaks = yellow
Each character needs 11 more bytes to contain color. (Same color in a
row could contain only one overhead but the logic how xxd creates colums
must be then changed.) Size of colored output is increased by factor of
~6. Also grepping the output will break when colors is used.
Flag for color is "-R", because less uses "-R".
Color uses parameters auto,always,never same as less and grep (among
others).
E.g.
xxd -R always $FILE | less -R
Add some screen-tests (that currently on work on linux) to verify the
feature works as expected.
closes: #12131
Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Aapo Rantalainen <aapo.rantalainen@gmail.com>
