Actually, $dir and $_ will only be interpreted by the shell if they contain "funny" characters. If a string passed as argument to qx or one-arg system contains just alphanums, underscores and whitespace, no shell gets involved, perl will call execv directly.

But obviously, if you don't know what $dir contains, you shouldn't use `ls $dir`, and if you aren't in control of the content of the directory you should use `cat $_`.

Even if you don't think that this is important in your case, it's better to make the code more maintainable and re-usable for security-aware scenarios.

I cannot agree with that, if only for the reasons it's often not mutually possible. More maintable code usually means simpler code, while code that needs to be run in a possible hostile environment tends to be more complex than code that doesn't have to run in such an environment. "More maintable" and "re-usable for security aware scenarios" are most of the time conflicting requirements.

In reply to Re^3: greater efficiency required (ls, glob, or readdir?) by JavaFan
in thread greater efficiency required (ls, glob, or readdir?) by jperlq

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.