fork and pipe

This is a discussion on fork and pipe within the C Programming forums, part of the General Programming Boards category; I need to use fork and pipe to read a text file. This is an assignment for a class. Basically, ...

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    fork and pipe

    I need to use fork and pipe to read a text file. This is an assignment for a class.

    Basically, I need to make 4 subprocesses to each read a portion of the input file, do some processing and return a result to the parent process so it can aggregate the children's results.

    From what I understand, I should use fork to create the children, then pipe to tell each child which part of the file to do.

    My question is, how do I use pipe. How do I know which child process I am talking to?

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    Quote Originally Posted by tbarsness View Post
    My question is, how do I use pipe. How do I know which child process I am talking to?
    You create a pipe by calling pipe(). You do this before you fork(). You know which process you are talking to, because each process has its own pipe.

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    Thanks, I will try fork() before pipe()

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    Quote Originally Posted by tbarsness View Post
    Thanks, I will try fork() before pipe()
    No no, pipe() before fork(). After the fork() it is too late.

    And you actually need two pipes per process. Pipes are one-way, but you need two-way communication. So each process needs two pipes, one for reading, one for writing.

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