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.

               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.


##</code><code>##

perl -e "umask 000; mkdir 'a', 0777";ls -ld a


##</code><code>##

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){$%++?$ %%2?push@C,$_,$":push@c,$_,$":(push@C,$_,$")&&push@c,$"}$C[$#C]=$/;($#C
>$#c)?($ c=\@C)&&($ C=\@c):($ c=\@c)&&($C=\@C);$%=$|;for(@$c){print$_^$$C[$%++]}