Scotmonk:

If the file is small enough that it fits comfortably in memory, you could just read the whole thing and then reverse it, like this:

# foo.pl - print a file in reverse

use strict;
use warnings;

my $FName = shift // die "Expected a filename!";
open my $FH, '<', $FName or die "Can't open $FName: $!\n";

# Read all the lines
my @lines = <$FH>;

# Reverse the order
@lines = reverse @lines;

for my $line (@lines) {
    print $line;
}

[download]

When I run it on itself, I get:

$ perl foo.pl foo.pl

}
    print $line;
for my $line (@lines) {

@lines = reverse @lines;
# Reverse the order

my @lines = <$FH>;
# Read all the lines

open my $FH, '<', $FName or die "Can't open $FName: $!\n";
my $FName = shift // die "Expected a filename!";

use warnings;
use strict;

# foo.pl - print a file in reverse

[download]

Sometimes a file is too big to handle that way, though that's increasingly rare with modern computers. But if so, you could always use a program (such as tac) that will reverse the file for you, and then you can process the file in order in your code.

For one-off jobs, that's the way I'd go. But if you always need to process the files in reverse, I'd use the File::Backwards module that stevieb suggested.

...roboticus

When your only tool is a hammer, all problems look like your thumb.

In reply to Re: Reading the contents of a file from the bottom up by roboticus
in thread Reading the contents of a file from the bottom up by Scotmonk

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