lanx@nc10-ubuntu:/tmp$ echo 1 > dir/tst.pm
lanx@nc10-ubuntu:/tmp$ chmod u-x dir
lanx@nc10-ubuntu:/tmp$ ll -d dir
drw-r-xr-x 2 lanx lanx 4096 2013-05-22 00:28 dir
lanx@nc10-ubuntu:/tmp$ perl -Idir -Mtst -e'1'
Can't locate tst.pm in @INC (@INC contains: dir /etc/perl /usr/local/lib/perl/5.10.0 /usr/local/share/perl/5.10.0 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.10 /usr/share/perl/5.10 /usr/local/lib/site_perl .).
BEGIN failed--compilation aborted.