How can Perl's system() print the command that it's running?

Question

In Perl, you can execute system commands using system() or `` (backticks). You can even capture the output of the command into a variable. However, this hides the program execution in the background so that the person executing your script can't see it.

Normally this is useful but sometimes I want to see what is going on behind the scenes. How do you make it so the commands executed are printed to the terminal, and those programs' output printed to the terminal? This would be the .bat equivalent of "@echo on".

Answer 1

Here's an updated execute that will print the results and return them:

sub execute {
  my $cmd = shift;
  print "$cmd\n";
  my $ret = `$cmd`;
  print $ret;
  return $ret;
}

Answer 2

Another technique to combine with the others mentioned in the answers is to use the tee command. For example:

open(F, "ls | tee /dev/tty |");
while (<F>) {
    print length($_), "\n";
}
close(F);

This will both print out the files in the current directory (as a consequence of tee /dev/tty) and also print out the length of each filename read.