pipe creates a pair of file descriptors, pointing to a pipe inode, and places
them in the array pointed to by
filedes . filedes[0] is for reading,
filedes[1] is for writing.
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and
errno is set appropriately.
ERRORS
EMFILE
Too many file descriptors are in use by the process.
