Cleaned up code with error checking: 
use strict;
use warnings;

use Fcntl qw( SEEK_SET );

my @files = <files*.txt>;

# Should really use File::Temp
my $fn_out = "tmp.txt";

my $error = 0;
for my $fn_in (@files) {
    open(my $fh_out, '>', $fn_out)
        or die("Can't create output file \"$fn_out\": $!\n");

    open(my $fh_in, '<', $fn_in)
        or do {
            warn("Can't open input file \"$fn_in\": $!\n");
            $error = 1;
            next;
        };

    my $sum = 0;
    my $cnt = 0;

    while (<$fh_in>) {
        chomp;
        $sum += ( split /\|/ )[2];
        ++$cnt;
    }

    my $avg = $sum / $cti;

    seek($fh_in, 0, SEEK_SET)
        or do {
            warn("Can't seek in input file \"$fn_in\": $!\n");
            $error = 1;
            next;
        };

    while (<$fh_in>) {
        chomp;
        my ($hd, $md, $tl) = split(/\|/, $_);
        my $tlf = sprintf("%.4f", $tl/$avg);
        print $fh_out "$hd|$md|$tlf\n";
    }

    close($fh_in);
    close($fh_out)
        or do {
            warn("Can't save to output file \"$fn_out\": $!\n");
            $error = 1;
            next;
        };

    rename($fn_out, $fn_in)
        or do {
            warn("Can't rename \"$fn_out\" to \"$fn_in\": $!\n");
            $error = 1;
            next;
        };
}

exit($error);

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In reply to Re^2: Batch processing of files by ikegami
in thread Batch processing of files by austinby

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