C:\>perldoc -f mkdir 
    mkdir FILENAME,MASK 
    mkdir FILENAME 
    mkdir   Creates the directory specified by FILENAME, with permissions 
            specified by MASK (as modified by "umask"). If it succeeds it 
            returns true, otherwise it returns false and sets $! (errno). If 
            omitted, MASK defaults to 0777. If omitted, FILENAME defaults to 
            $_. 
 
            In general, it is better to create directories with permissive 
            MASK, and let the user modify that with their "umask", than it 
            is to supply a restrictive MASK and give the user no way to be 
            more permissive. The exceptions to this rule are when the file 
            or directory should be kept private (mail files, for instance). 
            The perlfunc(1) entry on "umask" discusses the choice of MASK in 
            more detail. 
 
            Note that according to the POSIX 1003.1-1996 the FILENAME may 
            have any number of trailing slashes. Some operating and 
            filesystems do not get this right, so Perl automatically removes 
            all trailing slashes to keep everyone happy. 
 
            In order to recursively create a directory structure look at the 
            "mkpath" function of the File::Path module.