Annotation of /bin/block-devices

#!/usr/bin/perl

=head1 block-devices

Display all block devices on system

  hdparm -t `block-devices`

=cut

use warnings;
use strict;
#use autodie;

open(my $proc, '<', '/proc/partitions');

my @header;
my $last_device;

my $name2col;
sub col {
        my ( $name, $line ) = @_;
        if ( ! $name2col ) {
                $name2col->{ $header[$_] } = $_ foreach 0 .. $#header;
        }
        $line =~ s/^\s+// || die "expected line to start with space: $_\n";
        my @c = split(/\s+/, $line, $#header + 1 );
        return $c[ $name2col->{ $name } ];
}

while(<$proc>) {
        chomp;
        if ( ! @header ) {
                @header = split(/\s+/, $_);
                next;
        }
        next unless $_;

        my $device = col 'name', $_;
        if ( $last_device && substr( $device, 0, length($last_device) ) eq $last_device ) {
                warn "# partition $device\n";
        } else {
                print '/dev/', $last_device = $device, $/;
        }
}

1	dpavlin	12	#!/usr/bin/perl
2
3			=head1 block-devices
4
5			Display all block devices on system
6
7			hdparm -t `block-devices`
8
9			=cut
10
11			use warnings;
12			use strict;
13			#use autodie;
14
15			open(my $proc, '<', '/proc/partitions');
16
17			my @header;
18			my $last_device;
19
20			my $name2col;
21			sub col {
22			my ( $name, $line ) = @_;
23			if ( ! $name2col ) {
24			$name2col->{ $header[$_] } = $_ foreach 0 .. $#header;
25			}
26			$line =~ s/^\s+// \|\| die "expected line to start with space: $_\n";
27			my @c = split(/\s+/, $line, $#header + 1 );
28			return $c[ $name2col->{ $name } ];
29			}
30
31			while(<$proc>) {
32			chomp;
33			if ( ! @header ) {
34			@header = split(/\s+/, $_);
35			next;
36			}
37			next unless $_;
38
39			my $device = col 'name', $_;
40			if ( $last_device && substr( $device, 0, length($last_device) ) eq $last_device ) {
41			warn "# partition $device\n";
42			} else {
43			print '/dev/', $last_device = $device, $/;
44			}
45			}
46