Re: writing to the top of a file

Try this

#!/usr/bin/perl

use strict;
use warnings;

use Tie::File;
use Data::Dumper;

my $file = "file.txt";
my @lines;

#tie @lines, 'Tie::File', $file || die $!;
tie @lines, 'Tie::File', $file or die $!;

my @tmp = splice @lines;

push @lines, <STDIN>;
push @lines, @tmp;

untie @lines;
[download]

Tie::File isn't a standard module but its easily installed as it is pure Perl (i.e. doesn't need a C compiler installed).

Updated: changed '||' to 'or'.

Another update

Given that whatever solution you choose will be running from a web page (via CGI), have you given any thought file locking? What if multiple copies of the CGI script are running at the same time? You could potentially lose a lot of data...

Comment on Re: writing to the top of a file Download Code

Replies are listed 'Best First'.
Re: Re: writing to the top of a file by neniro (Priest) on May 20, 2004 at 10:01 UTC
unshift makes it simpler: `#!/usr/bin/perl use strict; use warnings; use Tie::File; my $file = "file.txt"; my $insert = shift @ARGV; chomp $insert; my @lines; tie @lines, 'Tie::File', $file or die $!; unshift @lines, $insert; # more simple, isn't it? untie @lines;` [download] best regards, neniro	[reply] [d/l]
Re: Re: writing to the top of a file by Somni (Friar) on May 20, 2004 at 03:23 UTC
Tie::File is core as of perl 5.8.	[reply]
Re: Re: writing to the top of a file by BrowserUk (Patriarch) on May 20, 2004 at 12:11 UTC
Using Tie::File this way will still need to read and write the whole file. This is much slower than simply reading to the end to get the last line. It also doesn't scale well for largish files, and doesn't address the concurrency issue. Examine what is said, not who speaks. "Efficiency is intelligent laziness." -David Dunham "Think for yourself!" - Abigail	[reply]


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