That works fine if access control is done solely by the standard permission bits. It fails is access control is done via ACLs, which allows making a file writeable for more than the owner of a file, without having to resort to groups. (One can only be a member of a limited number of groups, a number that quickly exceeds the number of permutations of a small group of people wanting to share files)

AFAIK, there's no way to ACL querying with just standard Perl. But I'd be surprised if there aren't CPAN modules available that will do ACL management for the more common systems out there (but I haven't checked).

In reply to Re^2: Writeability of a file for a different user by JavaFan
in thread Writeability of a file for a different user by InfiniteMonkey

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.