Does opening a pipeline in Perl involve a shell?

Question

If I do this in a Perl script on a Unix/Linux system:

open(my $fh, 'cat|');

is a shell involved? And if not, what about this:

open(my $fh, 'cat -v|');

I would like to avoid a shell, if possible, and I even know how to do it:

open(my $fh, '-|') || exec('cat', '-v');

but brevity is also valuable.

Answer 1

From open, following code examples

The last two examples in each block show the pipe as "list form", which is not yet supported on all platforms. A good rule of thumb is that if your platform has a real fork (in other words, if your platform is Unix, including Linux and MacOS X), you can use the list form. You would want to use the list form of the pipe so you can pass literal arguments to the command without risk of the shell interpreting any shell metacharacters in them. However, this also bars you from opening pipes to commands that intentionally contain shell metacharacters, [...]

(my emphasis)

The last example previous to this is

open(my $fh, "-|", "cat", "-n", $file);

which is incidentally almost exactly your example from the question.

So go with the "list form" and there's no shell. This goes for system as well (but, alas, not for qx)