use strict;
use warnings;

my @txtfiles = glob "*.txt";
my @criticalfiles;
for my $file (@txtfiles) {
        my $fh;
        if( not open $fh, "<", $file ) {
                print "Cannot open file $file, skipping.\n";
                next;
        }
        while( <$fh> ) {
                if( /critical/ ) {
                        push @criticalfiles, $file;
                        last;
                }
        }
        close $fh;
}
print "Critical files:\n";
print join( "\n", @criticalfiles ), "\n";
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