The code is correct, but confusing with all the 'if not's. See RMGir's reply above for an explanation of what the code does. However, to make it less confusing, here's a fork()ing framework that uses straight ifs that are easier to understand (at least for me):

use strict;
if (defined(my $pid=fork()) {
  if ($pid) {
  # $pid is not 0, so this is the parent
  # Let's redirect the user (more extensive code in your example).
  redirect_user();
  } else {
  # $pid=0, so this is the child
  my $retval=do_child_code();
  exit $retval;
  }
} else {
# Oops, fork() returned undef - something is definitely wrong.
  DieNice("Unable to fork: $!\n");
}

sub do_child_code {

  # Do your time consuming stuff, setting $retval to
  # a useful number
  return $retval;
}
[download]

You could do without the else block calling do_child_code, and have the child just fall through down to the child code, but this way it's a lot easier to understand and maintain.

CU
Robartes-

---

---

• Are you posting in the right place? Check out Where do I post X? to know for sure.
• Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:

  <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>

• Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
• Want more info? How to link or How to display code and escape characters are good places to start.