Creating Pipes From C Language



The system call pipe() creates a plumbing pipe
pipe(2) creates two descriptors, one WO and one RO
There fd's are not connected to the filesystem, they only live in the process
Thus, a pipe can only connect processes originating from the same grandparent

The C library also offsers popen(3)/pclose(3)
They use the same argument conventions as fopen(3)/fclose(3)
But you can't just fclose a file returned by popen
Popen invokes a shell process, so a whole command line is fine
The shell can be written-to or read-from
The code is much simpler than running pipe/fork/exec/wait
But there's less control over the details