I'm a bit new to IPC and forking.

I'm trying to read a series of CDs (for example 12 discs in a collection). I have 3 CD drives. I will fork a child process for each drive. The child will output a file, e.g. "disc1.wav" and then exit.

How can I best have the parent keep track of the number of discs so far read and pass the appropriate value to each child in sequence?

The scenario I fear:

Parent -> child 1, cdrom1 still reading disc1
       -> child 2, cdrom2 *finished* reading disc2 -> exit0
       -> child 3, cdrom3 still reading disc3

[download]
Child 2 exits as above. Next, the parent should fork another read child: 
Parent -> child 1, cdrom1 still reading disc1
       -> child 2 (done)
       -> child 3, cdrom3 still reading disc3
       -> child 4, cdrom2 read disc4

[download]
The parent should pass the disc number "4" do child 4 so it knows which disc its reading. Seems tricky! Any tips or tutorial links?

In reply to Efficient way to fork processes and keep a running count? by bfreemer

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.