Here is the part of old perl script I struggle with.
The variable $h suddenly defined inside of if and I cannot figure out what it means.

#!/usr/bin/perl

use strict;
use warnings;
use Scalar::Util qw(looks_like_number);

if (open(LIST,"/proc/partitions"))
{
    while (<LIST>)
    {
        my @a = split(/\s /); 
        print "@a\n";
        if (looks_like_number($a[3]) && $a[3] > 100000000)
        {
            if (open(IN, "/dev/$a[4]"))
            {
                my $h;
                if (read(IN, $h, 4) == 4 && $h eq 'EFI')
                {
                    print "/dev/$a[4]\n";
                }

                close(IN);
            }
        }
    }
}

It's actually a part of the code.

Anyway it's running well, but in my knowledge, nothing is saved to the variable $h and just defined.

Is it related with looks_like_number?

Can you tell me what I miss?

CodePudding user response：

It's written to by the read function:

read FILEHANDLE,SCALAR,LENGTH

Attempts to read LENGTH characters of data into variable SCALAR from the specified FILEHANDLE. Returns the number of characters actually read, 0 at end of file, or undef if there was an error (in the latter case $! is also set). SCALAR will be grown or shrunk so that the last character actually read is the last character of the scalar after the read.