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  1. #include <unistd.h>
  2.  
  3. int main() {
  4.     // create two pipes for communication
  5.     int back[2];
  6.     int forth[2];
  7.     pipe(back);
  8.     pipe(forth);
  9.  
  10.     // make a copy of this process
  11.     if(fork() == 0) {
  12.         // in that copy...
  13.         // set this process's stdin to be the read end of back
  14.         dup2(back[0], 0);
  15.         // and stdout to be the write end of forth
  16.         dup2(forth[1], 1);
  17.         // cleanup the now unnecessary pipe ends
  18.         close(back[0]); close(back[1]);
  19.         close(forth[0]); close(forth[1]);
  20.         // replace this process with the cat program
  21.         // it simply copies input from stdin to stdout
  22.         execlp("cat", "cat", 0); // never returns
  23.     }
  24.     // ... and in the original process
  25.     // write meow into the back pipe
  26.     write(back[1], "meow", 5);
  27.     // 
  28.     // set this process's stdin to be the read end of forth
  29.     dup2(forth[0], 0);
  30.     // and stdout to be the write end of back
  31.     dup2(back[1], 1);
  32.     // cleanup the now unnecessary pipe ends
  33.     close(back[0]); close(back[1]);
  34.     close(forth[0]); close(forth[1]);
  35.     // replace this one with cat too
  36.     execlp("cat", "cat", 0);
  37.  
  38.     // now each of the cat programs reads from the other's stdout
  39.     // and writes intp the other's stdin
  40.     // and we dropped a "meow" in the pipes
  41.     // do the math...
  42. }
  43.  
Time limit exceeded #stdin #stdout 5s 3780KB
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Standard input is empty
stdout
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Standard output is empty
https://ideone.com/Fam8o
language:
C++ (gcc 8.3)
created:
14 years ago
visibility:
public

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