Colors with unix command "watch"?
Do not use watch
... When you use watch programs can detect they're not writing to a terminal and then strip the color. You must use specific program flags to keep the control codes there.
If you don't know the flags or there isn't you can make a poor's man watch by:
while sleep <time>; do clear; <command>; done
It will have a bit of flicker (watch works "double buffered") but for some stuff it is useful enough.
You may be tempted to make a double buffered poor man's watch using
while sleep <time>; do <command> > /tmp/file; clear; cat /tmp/file; done
But then you'll hit again the "I am not writing to a terminal" feature.
You can duplicate the fundamental, no-frills operation of watch
in a couple lines of shell script.
$ cat cheapwatch #!/bin/sh# Not quite your Rolexwhile true ; do clear printf "[%s] Output of %s:\n" "$(date)" "$*" # "$@" <- we don't want to do it this way, just this: ${SHELL-/bin/sh} -c "$*" sleep 1 # genuine Quartz movementdone$ ./cheapwatch ls --color # no problem
Eventually, someone very clever will hack a tr
command into this script which strips control characters, and then force the user to use --color
to disable that logic. For the time being, the sheer naivete of this implementation is keeping the color-eating monster away.
If you're in a situation where watch
doesn't have the --color
option and you can't upgrade the package for whatever reason, maybe you can throw this in.