Question

If I create pipe in unix this way:

int fds[] = {0, 0};
pipe(fds);

Then make FILE * from fds[0] this way:

FILE *pipe_read = fdopen(fds[0], "rt");

Then how should I close this file (pipe_read)?

1. fclose(pipe_read)
2. pclose(pipe_read)
3. close(fileno(pipe_read))

Answer 1

fdopen returns a FILE* so you should fclose it. This will also close the underlying file descriptor as well.

The pclose call is meant for closing a handle created with popen, a function you use for running a command and connecting to it with pipes.

The close call will close the underlying file descriptor but, unfortunately, before the file handle has had a chance to flush its data out – in other words, you’re likely to lose data.