Then the sleep() should ensure the pid is not reused within the same tick, so it should still remain unique.

It does depend a bit on the precise sleep() implementation though; possibly safer (and a bit faster) would be:

  my $t = time;
  select(undef, undef, undef, 0.1) while time <= $t;
  $unique = "$t$$";

[download]

It also assumes a monotonically increasing time: if the sysadmin may correct a fast clock backwards, it would be very difficult to cope with. (Note that ntpd will adjust the time in increments of less than a second except when the clock error is "large"; once initially synchronised, a running system corrected by ntpd should never normally skip a full second forwards or backwards.)

Hugo

In reply to Re^4: Need to Generate Unique String by hv
in thread Need to Generate Unique String by EchoAngel

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.