Re^5: Print line from file only once even if occurrence of pattern is more than once in the line

Note that the lines could occur immediately after one another and I would like to have output print only once in such cases.

To avoid this, a solution using vec could work for you.

The line of code vec($vec, $_, 1) ||= 1 for $lo .. $hi; would assign a 1 to each position. So you wouldn't repeat a line when printing out the results.

my @log_lines=<$read_tmp_log>;
my $vec = '';

for my $i (0..$#log_lines) {
    next unless lc($log_lines[$i]) =~ /error|fatal|critical/;
    my $lo = $i - 5 < 0 ? 0 : $i - 5;;
    my $hi = $i + 5 > $#log_lines ? $#log_lines : $i + 5;
    vec($vec, $_, 1) ||= 1 for $lo .. $hi;
}

my $newline_needed = 0;
for my $i (0 .. $#log_lines) {
    if (vec($vec, $i, 1) == 1) {
        print $log_lines[$i];
        $newline_needed ||= 1;    
    }
    else {
        print "\n" if $newline_needed;    
        $newline_needed = 0;
    }
}
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