Why does grep lose colored output when executed from a bash script? [duplicate]

Answer 1

Looks like grep does not produce colors when not in interactive mode. You can force it to produce colored output:

grep --color=always $@

Answer 2

Grep has 3 color modes, Auto, Always, and Off.

Auto strips out the codes when it's connected to a non interactive output, such as a pipe (if you want to see why, try redirecting the output of grep --color=always into a file and then look at the file.. control codes everywhere)