I would like the output of A to be input for B and at the same time the output of B to be the input for A, is that possible? I tried the naïve thing: creating named pipes for A (pipeA) and B (pipeB) and then: pipeB | A | pipeA & pipeA | B | pipeB & But that does not work (pipeB is empty and switching the order would not help either). Any help would be appreciated. Example: Command A could be compiled form of this C program: #include <stdio.h> int main() { printf("0\n"); int x = 0; while (scanf("%d", &x) != EOF) { printf("%d\n", x + 1); } return 0; } Command B could be compiled form of this C program: #include <stdio.h> int main() { int x = 0; while (scanf("%d", &x) != EOF) { printf("%d\n", x + x); } return 0; }