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  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 248
  • Last Modified:

Perl File open and read in reverse

Here is what I have...

open (FILE1,"../gt/$in{'id'}/rafs.txt") || "Can't open filename1 $!";
while( <FILE1> ){
  chomp;
  my($count,$wa,$id,$n1,$e1,$n2,$e2,$n3,$e3,$n4,$e4)=split/\|/;

How can I make it open and read from bottom up?  I know reverse command, but not sure where to stick it in at.
0
precision
Asked:
precision
1 Solution
 
mjcoyneCommented:
#!/usr/bin/perl -w
use strict;

open (FILE1,"../gt/$in{'id'}/rafs.txt") or die "Can't open rafs.txt $!";

my @lines = <FILE1>;
@lines = reverse @lines;

for (@lines) {
  chomp;
  my($count,$wa,$id,$n1,$e1,$n2,$e2,$n3,$e3,$n4,$e4) = split/\|/;
}
0
 
ravenplCommented:
This will work for small files that fits into available memory. Otherwise smarter code is needed. The simplest way is to use existing sollutions

open(F, "tac 'filename' |") || die;
while(<F>)
{
 print($_);
}
close(F);
0
 
ozoCommented:
  use File::ReadBackwards ;

    tie *FILE1, 'File::ReadBackwards', "../gt/$in{'id'}/rafs.txt" or die "can't read '../gt/$in{'id'}/rafs.txt' $!" ;

    while( <FILE1> ) {
       chomp;
       my($count,$wa,$id,$n1,$e1,$n2,$e2,$n3,$e3,$n4,$e4)=split/\|/;
0
 
precisionAuthor Commented:
OZO

That seems like a very efficient way, I tried though and it crashed, I tried a few things but could not make run...
0
 
ozoCommented:
What did you try and how did it crash?
Do you have File::ReadBackwards installed?
0

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