TL;DR

A little note on Term::ANSIColor.

Sometime it’s handy to spice up the terminal output with some color, e.g. to underline some important part. Doing this has been super-easy since a long time in Perl, thanks to the core module Term::ANSIColor:

use Term::ANSIColor ':constants';
say BOLD, BLUE, 'wha',
    RED,        'tev',
    GREEN,      'ah!';
say RESET,      '(back...)';

output with color

This is implemented by interspersing escape sequences in the output, that are intercepted by the terminal application to e.g. change to bold or switch to a different color.

While useful, this can be detrimental when you look for data (e.g. with grep), because escape sequences will get in the way. For example, this:

$ ./ta.pl | grep whatevah

produces no output:

grep fails

We need the escape sequences to be disabled when the output is not to a terminal… which is what the -t test function helps us doing! So we can do this (order is important, put it before loading Term::ANSIColor!):

BEGIN{ $ENV{ANSI_COLORS_DISABLED} = 1 unless -t STDOUT }
use Term::ANSIColor ':constants';
say BOLD, BLUE, 'wha',
    RED,        'tev',
    GREEN,      'ah!';
say RESET,      '(back...)';

Setting environment variable ANSI_COLORS_DISABLED to a true vaue before loading the module (note the BEGIN block) puts the module in quiet mode and everything works as expected:

grep goes

Or… just use Term::ANSIColor::Conditional from CPAN 🤫