C:\>set
PERL5LIB=H:\devperl\tools;

C:\>perl -e"print qq( @INC )"
 H:\devperl\tools C:/Perl/lib C:/Perl/site/lib .

##</code><code>##

print "yes dir\n" if -d "c:\\perl/lib";
print "yes dir\n" if -d 'c:\perl/lib';

##</code><code>##

system "dir c:\\perl\\lib";