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?