How to delete a line with pattern matching

[briggs]

Hi All,
I have a file which the following data

This is a sample
tool error
end of file

I need to delete the line before tool error. I can read the file line by line and match for the key word " tool error", but not sure how to delete the line before the matched line.
Any pointers to solve this?, thnaks in advance

[toolic]

Keep a copy of the previous line, then only print the previous line if the match of the current line does not succeed (UNTESTED):

my $prev = <>;
while (<>) {
    print $prev unless /tool error/;
    $prev = $_;
}
print $prev;
 

[murugaperumal]

use the following code

 
use strict;
use warnings;
open FH,"<file2" or die "can't Open $!\n";
my $line;
my $flag=1;
 while($line=<FH>)
 {
     if($flag == 0)
     {
         print $line;
         next;
     }
     if($line=~/tool error/)
     {
         $flag=0;
         print $line;
     }
}