How would I add a prefix to input I receive from a pipe via awk and color the prefix conditionally? Is there a way to add a prefix to lines received (and filtered) via `awk` \- yes I know _that's_ possible so far - and then conditionally (e.g. based on the existence of the `$PS1` variable of the surrounding Bash script or `[ -t 1 ]`) color it using ANSI escape sequences? I know how to add a prefix using the `^` anchor and about two or three other ways and I know how to use escape sequences in Bash `echo` and `printf`. How - if at all - can I color the output produced by `awk` as outlined, based on a condition that can be evaluated inside an inline `awk` script? NB: I have `mawk` or `gawk` at my disposal, `mawk` is default.

if [ -t 1 ]; then
eval "$(printf 'COLOR_ON="\033[31m" COLOR_OFF="\033[m"')"
else
COLOR_ON= COLOR_OFF=
fi
export COLOR_ON COLOR_OFF
awk '{print ENVIRON["COLOR_ON"] "prefix: " ENVIRON["COLOR_OFF"] $0}'


Or:


[ ! -t 1 ]
awk -v color="$?" '{
print((color ? "\033[31m" : "") "prefix: " (color ? "\033[m" : "") $0)}'