Re^3: grep in line and print

[Athanasius]

With use strict in effect, you need to declare your variable names:

my $allmac = ...
...
        my $id = ...

But the line:

while (my $line = $allmac)

won’t work: it’s assigning the file name to $line, but it needs to call readline on a file handle, like so:

open (my $fh, '<', $allmac) or die "Can't open file '$allmac' for read
+ing: $!";

while (my $line = <$fh>)
{
    ....

Applying the diamond operator to a filehandle: <$fh> is the standard way to call readline in Perl. See readline and I/O Operators; also open and perlopentut.

Hope that helps,