open - open for reading or writing
Open opens the file name for reading (if mode is 0), writing (if mode
is 1) or for both reading and writing (if mode is 2). Name is the
address of a string of ASCII characters representing a path name, ter-
minated by a null character.
The file is positioned at the beginning (byte 0). The returned file
descriptor must be used for subsequent calls for other input-output
functions on the file.
creat(2), read(2), write(2), dup(2), close(2)
The value -1 is returned if the file does not exist, if one of the nec-
essary directories does not exist or is unreadable, if the file is not
readable (resp. writable), or if too many files are open.
(open = 5.)
sys open; name; mode
(file descriptor in r0)