bash watch command with colors preserved

Question

From man watch:

Non-printing characters are stripped from program output. Use "cat -v" as part of the command pipeline if you want to see them.

So how do I use cat -v if I want to see the colored output from:

watch ls -al --color

Answer 1

The right command is

watch --color "ls -a1 --color"

It isn't documented in the man page or the --help screen. I has to use strings to find it.

Answer 2

I think it may not be possible with the 'watch' command. Here is a longer way of doing it:

while true; do clear; date;echo;ls -al --color; sleep 2; done

You could put this in a script, for example:

echo "while true; do clear; date;echo;\$*;sleep 2; done" > watch2
chmod +x watch2
./watch2 ls -al --color

---

To clarify, here's why I think it's not possible with the 'watch' command. See what happens if you use cat -v:

watch "ls -al --color|cat -v"

It shows you the color control characters...which I think is not what you want.

Answer 3

watch doesn't work with color output and I know of no way to make it do it. You can create your own script to emulate it, though.