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Thanks for the this. In my opinion, there's too little written about passing fd's (use of dup2). It seems like a technique that is more useful than just as pa

Thanks for the this. In my opinion, there's too little written about passing fd's (use of dup2). It seems like a technique that is more useful than just as part of shell redirection. Safer than popen()?

dllthomas 14y ago
I'm pretty sure popen is just a wrapper around this stuff. It's basically, pipe: get two fds connected by a pipe fork: create a child process dup2: move the read fd of the pipe to 0 (stdin) in the new process exec: run the program in the child process There's some cleanup but that's the gist - popen isn't a syscall (or reasonably close to one), so must necessarily rely on other stuff to get its work done where it actually interfaces with the kernel.
- deleted 14y ago
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- wethesheeple 14y ago
  That makes perfect sense. It's the fork+exec that makes it dangerous (e.g. in the CGI context). This is something I've been wondering about and you have just provided a jolt of clarity. Many thanks, again.
  - dllthomas 14y ago
    Happy to help :)