How do I read a file line by line in reverse order (from EOF to start of file)

elanajk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: How do I read a file line by line in reverse order (from EOF to start of file) by particle (Vicar) on Jul 05, 2001 at 23:03 UTC
you may find this node helpful... Is there a way to read a file backwards? ~Particle	[reply]
Re: How do I read a file line by line in reverse order (from EOF to start of file) by swngnmonk (Pilgrim) on Jul 05, 2001 at 23:58 UTC
If you're on a unix (at least Linux) system, you can use the command 'tac' to reverse the lines in a file. so: `$/ = "\n"; open(REVERSE_FILE, "\|/usr/bin/tac $filename"); while (<REVERSE_FILE>) { print "$_\n"; } close REVERSE_FILE;` [download]	[reply] [d/l]
Re: Answer: How do I read a file line by line in reverse order (from EOF to start of file) by Anonymous Monk on Dec 01, 2002 at 20:02 UTC
I will put the pipe at the end: `"/usr/bin/tac $filename \|"`	[reply] [d/l]
Re: How do I read a file line by line in reverse order (from EOF to start of file) by kryberg (Pilgrim) on Oct 23, 2002 at 16:21 UTC
`open( FILE, "<$file_to_reverse" ) or die( "Can't open file file_to_reverse: $!" ); @lines = reverse <FILE>; foreach $line (@lines) { # do something with $line }` [download] Reference Chapter 8 of the Perl Cookbook.	[reply] [d/l]
Re: How do I read a file line by line in reverse order (from EOF to start of file) by jdporter (Paladin) on Jul 07, 2006 at 13:13 UTC
You could use File::ReadBackwards. Even better, imho, would be to use Tie::File, which maps the lines of a file into an in-memory array; then you'd simply traverse that array in descending index order. `use Tie::File; tie my @lines, 'Tie::File', $filename; for my $i ( reverse 0 .. $#@lines ) { do_something_with( $lines[$i] ); }` [download]	[reply] [d/l]