Something I find quite helpful with one liners is B::Deparse:

>perl -MO=Deparse -lne "printf qq([%s] => %02x\n), $_, ord $_ for spli
+t //"

BEGIN { $/ = "\n"; $\ = "\n"; }
LINE: while (defined($_ = <ARGV>)) {
    chomp $_;
    printf "[%s] => %02x\n", $_, ord $_ foreach (split(//, $_, 0));
}
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So that program goes through the input, splits it between each byte, and then feeds each byte as a character and as the number to the printf function.