Print line from file only once even if occurrence of pattern is more than once in the line

[jayu_rao]

Hi Monks,

I have written a code that matches the occurrence of the words like Error / Fatal etc from a log file and printing it to a temporary file.

However, the problem is that the words can occur more than once in a line like " ERROR - Critical error" or something like FATAL - Fatal error and this causes the lines to get printed more than once because of the patterns getting repeated more than once.

Can someone help me in suggesting a way to print the lines only once per occurrence in a line with an example?

Regards,

Jay

[LanX]

You most likely have a loop over lines doing different checks.

Use next after the first successful match to parse the next line.

Otherwise you should show us some code of what you tried, such that we understand were your problem is.

See also How do I post a question effectively?

[jayu_rao]

Thanks Rolf. You are right. The code snippet is as below:

my @log_patterns = (
qr/ERROR/,
qr/Error/,
qr/FATAL/i,
qr/critical/i,
);

my @log_lines=<$read_tmp_log>;
my $i;
my $j;

for (@log_patterns){
  for $i (0..$#log_lines) {
    next unless $log_lines[$i] =~ $_;
    my $a = $i - 5 < 0 ? 0 : $i - 5;;
    my $b = $i + 5 > $#log_lines ? $#log_lines : $i + 5;
    print $output_file "\n";
    for $j($a..$b){ 
      print $output_file $log_lines[$j]; 
   }
 }
}

[pme]

Hi jayu_rao,

Try to do this way:

while(<$read_tmp_log>) {            # reads input line
  if ( /error|fatal|critical/i ) {  # if the line contains error, fata
+l or critical case insensitively
    ...  # process data
  }
}

[LanX]

Ehm...What's the difference to the question you already asked two weeks ago?

Print 5 lines before and after pattern match from a list

[kcott]

G'day jayu_rao,

You're going to have to show us some of this code you've written to get any sort of reasonable answer. The problem could be a major design flaw, a typo in a regex, or something else: we don't know.

[See guidelines: How do I post a question effectively?]

[CountZero]

It would indeed help if at least you show us the regex you are using.

[sandy105]

i wrote something similar a while back .

@line = <filehandle> #filehandle used for opening the file

foreach my $line (@lines) {
            
              #note i am matching a line  doing something like printin
+g and then using next ..
              if($line =~/^ProcessName:/){
                $mess = substr $keyword , 13;
                $unirec{$id} .="$date,$id,$mess\n";

                next;
                }
              
              if($line =~/^Process Message :/ ){
                $mess = substr $keyword , 18;
                $unirec{$id} .="$date,$id,$mess\n";

                next;
                }
              
              
       }