My suggestion would be to use the time function from Time::HiRes. 

use Time::HiRes qw[time];

printf "%.6f\n", time for 1..10;
1054051486.970288
1054051486.980302
1054051486.990316
1054051487.000331
1054051487.010345
1054051487.010345
1054051487.020360
1054051487.030374
1054051487.040388
1054051487.050403

[download]
That should give you a unique time (to the microsecond if your platform supports it), and should be okay until something like 2038?

Update: The timestamp is only a starting point.
If you are creating your temp files on shared media (suggestion:Don't!), or if you are running on a multi-processor machine, then you would need to combine the timestamps with additional information to aceive uniqueness. Processor ID in the latter case would work.
In the former case, which I would advise against, but if you have access to the hardcoded MAC addresses, this is a good starting point.

A bonus is that the resultant filenames are easily compared so cleaning up the directory periodically should be trivial.

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller

In reply to Re: Automatically creating incremental file names by BrowserUk
in thread Automatically creating incremental file names by Anonymous Monk

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.