For performance and sanity my routine will first do a test for file-existance and then try to glob it. It feels clumsy, though.

You need to check for file-existance afterwards, not beforehand. glob is not guaranteed to produce a list of existing files. For example, glob('file{a,b}') will return filea and fileb whether either, neither or both exists. 

@list = bsd_glob('~gnat', GLOB_ERR);

die("Unable to glob: $!\n")
   if GLOB_ERROR;

# Keep only references to existing files.
@list = grep -f, @list;

die("glob returned no existing results\n")
   if not @list;

[download]

I am still confused about the way $! behaves in this case

This case is not special. 

# XXX WRONG
$rv = print $fh (...);
if ($!) {
   die("Unable to write to file: $!\n")
}

# Ok
$rv = print $fh (...);
if ($rv) {
   die("Unable to write to file: $!\n")
}

[download]

In reply to Re^2: bsd_glob does not reset $! (The lessons learned) by ikegami
in thread bsd_glob does not reset $! by stefan k

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.