phpman > perldoc > tty(4)

Found in /usr/share/perl/5.34/pod/perlfaq3.pod
  Is there a pretty-printer (formatter) for Perl?
    Perl::Tidy comes with a perl script perltidy which indents and reformats
    Perl scripts to make them easier to read by trying to follow the rules
    of the perlstyle. If you write Perl, or spend much time reading Perl,
    you will probably find it useful.

    Of course, if you simply follow the guidelines in perlstyle, you
    shouldn't need to reformat. The habit of formatting your code as you
    write it will help prevent bugs. Your editor can and should help you
    with this. The perl-mode or newer cperl-mode for emacs can provide
    remarkable amounts of help with most (but not all) code, and even less
    programmable editors can provide significant assistance. Tom
    Christiansen and many other VI users swear by the following settings in
    vi and its clones:

        set ai sw=4
        map! ^O {^M}^[O^T

    Put that in your .exrc file (replacing the caret characters with control
    characters) and away you go. In insert mode, ^T is for indenting, ^D is
    for undenting, and ^O is for blockdenting--as it were. A more complete
    example, with comments, can be found at
    <http://www.cpan.org/authors/id/T/TO/TOMC/scripts/toms.exrc.gz>