Re: seek in a text file

truncate + tell

Update: Code:

#!/bin/perl -w
use strict;


my $file="dogy";
open(FH, "+<$file");
flock(FH, 2);
my @newEntries;
while(my $line = <FH>) {
    chomp($line);

    if ($line%2==1) { next; }
    push(@newEntries,$line);
}

seek FH,0,0;
foreach my $ent (@newEntries) {
    print FH $ent . "\n";
}

truncate FH, tell FH;

close(FH)
[download]

Update: Even better?

#!/bin/perl -w
use strict;


my $file="dogy";
open(FH, "+<$file");
flock(FH, 2);
my @newEntries;
while(my $line = <FH>) {
    chomp($line);

    if ($line%2==1) { next; }
    push(@newEntries,$line);
}

seek FH,0,0;
truncate FH, 0;
foreach my $ent (@newEntries) {
    print FH $ent . "\n";
}

close(FH)
[download]

Comment on Re: seek in a text file Select or Download Code

Replies are listed 'Best First'.
Re^2: seek in a text file by jwkrahn (Abbot) on Oct 06, 2008 at 04:45 UTC
Or even better? `#!/usr/bin/perl use warnings; use strict; use Fcntl qw/ :seek :flock /; my $file = 'dogy'; open my $FH, '+<', $file or die "Cannot open '$file' $!"; flock $FH, LOCK_EX or die "Cannot flock '$file' $!"; my @newEntries = grep !($_ % 2), <$FH>; seek $FH, 0, SEEK_SET or die "Cannot seek '$file' $!"; truncate $FH, 0 or die "Cannot truncate '$file' $!"; print $FH @newEntries; close $FH;` [download]	[reply] [d/l]
Re^2: seek in a text file by catfood (Novice) on Oct 06, 2008 at 01:18 UTC
works good, thanks.	[reply]