Your filesystem is probably case insensitive. Perl decides whether you have the module by seeing whether it can find the corresponding file. Since your filesystem doesn't seem to know the difference between Socket.pm and socket.pm, it happily reports that IO::socket is available.

That being said, I am on a Mac. (OS X)

---

$perl 
print $^O . "\n";
darwin
[download]

---

I would've thought that it would be case sensitive (it claims to be BSD based).

Check out: http://perldoc.perl.org/perlmacosx.html#Known-problems

Mac is case insensitive, despite its BSD heritage.

Takes two seconds to test...

• You can load the same module twice.
• The module's import won't get called since Perl will be looking in the wrong package.

C:\>perldoc -l IO::Socket IO::socket CGI
C:\Perl\lib\IO\Socket.pm
C:\Perl\lib\IO\socket.pm
C:\Perl\lib\CGI.pm
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Are you using cygwin? It has also similar methods to ensure unix programs work.

You can always see that on Win:

C:\Dokumente und Einstellungen\chris\Desktop>perldoc -l IO::Socket
C:\strawberry-perl\perl\site\lib\IO\Socket.pm

C:\Dokumente und Einstellungen\chris\Desktop>perldoc -l IO::sOCket
C:\strawberry-perl\perl\site\lib\IO\sOCket.pm
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Well I would not be surprised on windows as file-paths in windows are case insensitive anyway.

If this is indeed an ActiveState issue, then this is a serious bug. I read up the perldoc for require and it does not indicate that the search be case insensitive. For example, try below:

---

File listing:

$ls -al
total 112
$ls -1
Interface
Parser
Parser.pm
filetest.pl
loadme.pl
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---

Test code:

$cat filetest.pl 
#!/usr/local/ActivePerl-5.10/bin/perl
#===============================================
#
#         FILE:  filetest.pl
#
#        USAGE:  ./filetest.pl 
#
#  DESCRIPTION:  
#
#      OPTIONS:  ---
# REQUIREMENTS:  ---
#         BUGS:  ---
#        NOTES:  ---
#      VERSION:  1.0
#      CREATED:  10/12/2009 15:16:25 EDT
#     REVISION:  ---
#===============================================

use strict;
use warnings;


use FindBin qw($Bin);
my $good_filename = 'loadme.pl';
my $bad_filename = 'Loadme.pl';

print "Found $Bin/$good_filename" . "\n" if (-e $Bin . '/' . $good_fil
+ename);
print "Found $Bin/$bad_filename" . "\n" if (-e $Bin . '/' . $bad_filen
+ame);
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---

Run results:

$./filetest.pl 
Found /Volumes/UserData/Users/dattanik/Programs/Perl/Work_area/Admin_s
+erver/lib/Admin_server/loadme.pl
Found /Volumes/UserData/Users/dattanik/Programs/Perl/Work_area/Admin_s
+erver/lib/Admin_server/Loadme.pl
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...does not indicate that the search be case insensitive

No, but clearly indicated, in the equivalent code, is the fact that each module name is held as a key in %INC i.e. the underlying OS is responsible only for returning the/a requested file - thus only on a case-sensitive OS will require Foo; and require FoO; equate to different module implementation files being included i.e. on a case-insensitive OS, both require Foo; & require FoO; equate to the same module implementation file being included.

A user level that continues to overstate my experience :-))

Looks to me as if it is a local issue with your perl installation (maybe ActivePerl?).

I gave it a try with my self compiled perl and got:

$ perldoc -l IO::Socket IO::socket CGI
No documentation found for "IO::socket".
/usr/local/lib/perl5/5.10.1/i686-linux/IO/Socket.pm
/usr/local/lib/perl5/5.10.1/CGI.pm
$  perl -MIO::socket -e1
Can't locate IO/socket.pm in @INC (@INC contains: /usr/local/lib/perl5
+/5.10.1/i686-linux /usr/local/lib/perl5/5.10.1 /usr/local/lib/perl5/s
+ite_perl/5.10.1/i686-linux /usr/local/lib/perl5/site_perl/5.10.1 .).
BEGIN failed--compilation aborted.
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(I added CGI to test if multiple arguments are OK)

As I currently don't have an ActivePerl at hand, I cannot test furthermore.