my $line = <$fh>;
my @lines = <$fh>;
my $lines = do { local $/; <$fh> };

open(my $bigfile, '<', '/mein/grosse/datei')
or die "Error opening file: $!";
my @data = <$bigfile>;
close($bigfile);

#!/usr/bin/perl
use strict;
use warnings;

open my $fh, '>', 'foo.txt' or die $!;
for (1..10) {
    print $fh "$_ Perl slogan: Easy things should be easy,";
    print $fh " and hard things should be possible.\n";
}
close $fh;

#!/usr/bin/perl
use strict;
use warnings;

open my $fh, '<', 'foo.txt' or die $!;
seek($fh, 0, 2);
print "File size: ", tell($fh), "\n";
print "Change file and press enter ....\n";
<STDIN>; # jetzt editiere die Datei
seek($fh, 0, 2);
print "New file size: ", tell($fh), "\n\n";
seek($fh, 0, 0);
print <$fh>;
close $fh;

#!/usr/bin/perl
use strict;
use warnings;

open my $fh, '>>', 'foo.txt' or die $!;
print $fh "hello world\n";
close $fh;

File size: 791
Change file and press enter ....

New file size: 803

1 Perl slogan: Easy things should be easy, and hard things should be possible.
2 Perl slogan: Easy things should be easy, and hard things should be possible.
3 Perl slogan: Easy things should be easy, and hard things should be possible.
4 Perl slogan: Easy things should be easy, and hard things should be possible.
5 Perl slogan: Easy things should be easy, and hard things should be possible.
6 Perl slogan: Easy things should be easy, and hard things should be possible.
7 Perl slogan: Easy things should be easy, and hard things should be possible.
8 Perl slogan: Easy things should be easy, and hard things should be possible.
9 Perl slogan: Easy things should be easy, and hard things should be possible.
10 Perl slogan: Easy things should be easy, and hard things should be possible.
hello world

#> ls -li foo.txt
1818651 -rw-r----- 1 bloonix bloonix 803 2007-10-22 17:21 foo.txt

#> ls -li foo.txt
1818652 -rw-r----- 1 bloonix bloonix 815 2007-10-22 17:24 foo.txt