I don't know if this is the best way (perhaps there's a module to help maintain this kind of thing?), but you could use something like this with an array of the possible commands.. The array lets you fix the order the cmds are checked for (perhaps putting the common ones first), and if you capture in the regex, the captured values will be pased as parameters to the sub when it's invoked. Below is a working proof of concept:

use strict;
use warnings;
my @CMDS = (
  { regex => qr/^cp\s+(\S+)\s+(\S+)/, code => \&do_cp },
  { regex => qr/^mv\s+(\S+)\s+(\S+)/, code => \&do_mv },
);
my $input_string = <STDIN>;
foreach my $cmd ( @CMDS ){
  my @match = ($input_string =~ /$cmd->{regex}/) or next;
  $cmd->{code}( @match );
}
sub do_cp {
  my $src = shift;
  my $dest = shift;
  warn "cp $src $dest";
}
sub do_mv {
  my $src = shift;
  my $dest = shift;
  warn "mv $src $dest";
}
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