You're right about system() waiting for a child process to complete, but exec() works differently. It basically calls the program that you specify and kills the script that's currently running (unless the command can't run, in which case it will return false and put something interesting in $!). Generally I'd use exec() after forking, and use system() when you expect your external command to return in a timely fashion (In fact, system forks then execs and waits for the child to return before giving control back to the script). If you want to display an animated 'waiting' gif or something like it, system() would probably be the one you want.

In either case, you should enclose your command in quotes or generate an array with your command as the first element and it's arguments as the remaining elements:

system("/path/to/BlastTool my params here") or die "Could not run command";

or: 
@command = ("command", "my", "params", "here");
system(@command) or die;

[download]

In reply to Re^2: Executing one script with another by socketdave
in thread Executing one script with another by MonkPaul

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.