2.9BSD/usr/man/cat2/open.2

OPEN(2)             UNIX Programmer's Manual              OPEN(2)

NAME
     open - open for reading or writing

SYNOPSIS
     #include <sys/types.h>
     #include <sys/file.h>

     open(name, mode)
     char *name;

DESCRIPTION
     _O_p_e_n opens the file _n_a_m_e for reading (if _m_o_d_e is
     FATT_RDONLY), writing (if _m_o_d_e is FATT_WRONLY) or for both
     reading and writing (if _m_o_d_e is FATT_RDWR).  _N_a_m_e is the
     address of a string of ASCII characters representing a path
     name, terminated 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.

ERRORS
     The named file is opened unless one or more of the following
     is true:

     [EINVAL]            The path name contains a non-ASCII byte.

     [ENOTDIR]           A component of the path prefix is not a
                         directory.

     [EACCES]            A component of the path prefix denies
                         search permission.

     [ENOENT]            The named file does not exist.

     [EISDIR]            The named file is a directory and the
                         arguments specify it is to be opened for
                         writing.

     [EROFS]             The named file resides on a read-only
                         file system and the file is to be modi-
                         fied.

     [EMFILE]            The maximum number of file descriptors
                         allowed are already open.

     [ETXTBSY]           The file is a pure procedure (shared
                         text) file that is being executed and
                         the _o_p_e_n call requests write access.

     [EFAULT]            _N_a_m_e points outside the process's allo-
                         cated address space.

Printed 5/23/83                                                 1

OPEN(2)             UNIX Programmer's Manual              OPEN(2)

     [ELOOP]             Too many symbolic links were encountered
                         in translating the path name.

SEE ALSO
     close(2), creat(2), dup(2), read(2), write(2)

ASSEMBLER
     (open = 5.)
     sys open; name; mode
     (file descriptor in r0)

Printed 5/23/83                                                 2