color.pl

#!/usr/bin/env perl
use strict;
use warnings;
use utf8;
{
    no strict 'refs';
    my @color = qw(black red green yellow blue magenta cyan white);
    for (0..$#color) {
        my ($c, $n) = ($color[$_], 30 + $_);
        *$c = sub { -t *STDOUT ? "\e[1;${n}m@_\e[m" : "@_" };
    }
}


print black("black"), "\n";
print green("success"), "\n";
print red("error"), "\n";
print yellow("yellow"), "\n";
print blue("blue"), "\n";
print magenta("magenta"), "\n";
print cyan("cyan"), "\n";
print white("white"), "\n";

constant.pl

#!/usr/bin/env perl
use strict;
use warnings;
use utf8;
use constant INTERACTIVE => -t *STDOUT;
sub green { INTERACTIVE ? "\e[1;32m@_\e[m" : "@_" }
sub red   { INTERACTIVE ? "\e[1;31m@_\e[m" : "@_" }
sub white { INTERACTIVE ? "\e[1;37m@_\e[m" : "@_" }

simple.pl

#!/usr/bin/env perl
use strict;
use warnings;
use utf8;
sub red   { -t *STDOUT ? "\e[1;31m@_\e[m" : "@_" }
sub green { -t *STDOUT ? "\e[1;32m@_\e[m" : "@_" }
sub white { -t *STDOUT ? "\e[1;37m@_\e[m" : "@_" }