Redirecting input and output of a child process in C

Question

I want to write a c program in which i create multiple child processes and redirect their inputs and outputs to different file descriptors .I googled a lot but couldn't find relevant results. Please help .

See http://stackoverflow.com/questions/584868/rerouting-stdin-and-stdout-from-c — jweyrich, May 09 '11 at 14:20

score 3 · Answer 1 · answered May 09 '11 at 14:21

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Start with dup. You really need to search a bit harder. There is plenty of material on this.

answered May 09 '11 at 14:21

Duck

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score 2 · Answer 2 · answered May 09 '11 at 14:21

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The answer depends on your operating system. On UNIX-like systems, you use dup() and dup2() to copy file descriptors around; each child process will inherit the current set of file descriptors from the parent when it is exec-ed. So typically you fork the child process, set file descriptors 0, 1, and 2 to whatever you want them to be, and then exec() the actual child program.

answered May 09 '11 at 14:21

Ernest Friedman-Hill

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Since the phrase "file descriptors" was used, then I guess it must be UNIX/Linux. For completeness: on Windows use CreateProcess and look at the last three members of the STARTUPINFO struct. – cdarke May 09 '11 at 14:48

score 1 · Answer 3 · answered May 09 '11 at 15:21

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My favorite is forkpty. This function forks a child and give you a file descriptor to its stdin/stdout. You can use exec after forking,

answered May 09 '11 at 15:21

eyalm

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Redirecting input and output of a child process in C

3 Answers3