$ perl -le'print 0 + "0777"' 777 $ perl -le'print 0 + 0777' 511 $ perl -e'mkdir "testone", 0777 or die "Cannot mkdir testone because: $!"' $ ls -dl testone drwxr-xr-x 2 john john 4096 2012-12-20 21:12 testone $ rmdir testone $ perl -e'mkdir "testone", "0777" or die "Cannot mkdir testone because: $!"' $ ls -dl testone dr----x--t 2 john john 4096 2012-12-20 21:13 testone $ rmdir testone