Fellow Monks,
I must confess I am confused.

In one of my programs I concatenate some user-provided strings to build a file-match pattern which I then feed to bsd_glob from the File::Glob module. Then I need to detect whether it matched some files and proceed doing something with them. Sounds quite straightforward to me. But during this I ran into a strange runtime behaviour that I could boil down to the following test script:

#! /usr/bin/perl

use strict;
use warnings;
use Data::Dumper;
use File::Glob qw/:glob/;

# There lives a file "passwords.dat" in the current directory....

# This matches the whole filename. OK
my $pat1 = "passwords.dat";
print "\nPATT $pat1\n";
print "PRE  ERR: ", Dumper($!);
my @list = bsd_glob($pat1, GLOB_ERR);
print Dumper(\@list);
print "POST ERR: ", Dumper($!);
print "\n";

# This file is not there so it doesn't match and afterwards $! ist
# set. OK
my $pat2 = "this_will_miss_in_globbing";
print "\nPATT $pat2\n";
print "PRE  ERR: ", Dumper($!);
@list = bsd_glob($pat2, GLOB_ERR);
print Dumper(\@list);
print "POST ERR: ", Dumper($!);
print "\n";

# This should match again since it is just the same as the first match
# but *afterwards $! ist still set*!!??
my $pat3 = "passwords.dat";
print "\nPATT $pat3\n";
print "PRE  ERR: ", Dumper($!);
@list = bsd_glob($pat3, GLOB_ERR);
print Dumper(\@list);
print "POST ERR: ", Dumper($!);
print "\n";

# This resets $! back to normal which is just fine
my $pat4 = "*.dat";
print "\nPATT $pat4\n";
print "PRE  ERR: ", Dumper($!);
@list = bsd_glob($pat4, GLOB_ERR);
print Dumper(\@list);
print "POST ERR: ", Dumper($!);
print "\n";
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Using GLOB_ERR or GLOB_NOCHECK or both of them changes nothing. Now my questions are

• Why is the variable $! not reset back to normal on successful glob with $pat3?
• How do I get bsd_glob() to do just that?
• What is The Right Way to check the outcome of bsd_glob?

I assume that the error is on my side since this module is a core module which is even used to implement Perls glob() built-in.