sub text_to_shell_lit(_) {
   return $_[0] if $_[0] =~ /^[a-zA-Z0-9_\-]+\z/;
   my $s = $_[0];
   $s =~ s/'/'\\''/g;
   return "'$s'";
}

system(q{ssh -o StrictHostKeyChecking=no root@localhost }.text_to_shell_lit(q{/usr/bin/perl -i -pe}.text_to_shell_lit("s/^\Q$pat\E\$/\Q$repl\E/").q{ hashfile}));