Script to check terminal color support

256-color.pl

#!/usr/bin/env perl

use warnings;
use strict;

foreach my $red ( 0..5 ) {
    foreach my $green ( 0..5 ) {
        foreach my $blue ( 0..5 ) {
            printf(
                "\x1b]4;%d;rgb:%2.2x/%2.2x/%2.2x\x1b\\",
                16 + ( $red * 36 ) + ( $green * 6 ) + $blue,
                $red   ? ( $red   * 40 + 55 ) : 0,
                $green ? ( $green * 40 + 55 ) : 0,
                $blue  ? ( $blue  * 40 + 55 ) : 0,
            );
        }
    }
}

foreach my $gray ( 0..5 ) {
    my $level = ( $gray * 10 ) + 8;
    printf(
        "\x1b]4;%d;rgb:%2.2x/%2.2x/%2.2x\x1b\\",
        232 + $gray, $level, $level, $level
    )
}

print "System colors\n";
print "\x1b[48;5;${_}m  " for ( 0..7 );
print "\x1b[0m\n";
print "\x1b[48;5;${_}m  " for ( 8..15 );
print "\x1b[0m\n\n";

print "Color cube, 6x6x6:\n";
foreach my $green ( 0..5 ) {
    foreach my $red ( 0..5 ) {
        foreach my $blue ( 0..5 ) {
            my $color = 16 + ( $red * 36 ) + ( $green * 6 ) + $blue;

            print "\x1b[48;5;${color}m  ";
        }
        print "\x1b[0m ";
    }
    print "\n";
}

print "\nGrayscale ramp:\n";
print "\x1b[48;5;${_}m  " for ( 232..255 );
print "\x1b[0m\n";