## incorrect
shell> perl -e 'mkdir "foo", "0755"' && ls -ld foo
d-wxr----t    2 perl      monks          1024 May 28 14:50 foo
shell> rmdir foo
## correct
shell> perl -e 'mkdir "foo", 0755' && ls -ld foo
drwxr-xr-x    2 perl      monks          1024 May 28 14:50 foo