[Techtalk] Open file descriptors

[David Sumbler]

I originally asked this question on NewChix.  Unfortunately I had no
replies, but I am sure that somebody out there must know the answer.

So I hope that you won't mind me repeating it on TechTalk.

This was my question:

Amongst the options detailed by 'man initlog' are:

-c. --cmd=[program]
              Execute the specified program, logging anything output to stdout
              or stderr.

-r. --run=[program]
              Execute the specified program, with an open file
              descriptor so that the program can pass back
              commands to initlog.

Could somebody explain to me what an "open file descriptor" is, and
how the execution of a program using '-r' is different from using
'-c'?  How does the program "pass back commands to initlog"?

Thanks in advance for any help.

David

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