ken@ganymede: ~/tmp
$ echo $PS1
\[\033[0;36m\]\u@\h: \w\n\$ \[\033[0m\]
ken@ganymede: ~/tmp
$ perl -Mstrict -Mwarnings -E '
    my %escape = (
        h => do {my $x = `hostname`; chomp $x; $x},
        n => "\n",
        u => $ENV{USER},
        w => $ENV{PWD} =~ s/^$ENV{HOME}/~/r,
    );
    my $string = q{\u@\h: \w\n$ };
    $string =~ s/\\([hnuw])/$escape{$1}/g;
    say $string;
'
ken@ganymede: ~/tmp
$ 
ken@ganymede: ~/tmp
$