Arguments

 

file_spec

   A null-terminated character string containing a valid file
   specification. If you specify a directory in the file_spec and
   it is a search list that contains an error, VSI C interprets
   it as a file open error.

   If the file_spec parameter refers to a symbolic link, the open
   function opens the file pointed to by the symbolic link.
 

flags

   The following values are defined in the <fcntl.h> header file:

   O_RDONLY   Open for reading only
   O_WRONLY   Open for writing only
   O_RDWR     Open for reading and writing
   O_NDELAY   Open for asynchronous input
   O_APPEND   Append on each write
   O_CREAT    Create a file if it does not exist
   O_TRUNC    Create a new version of this file
   O_EXCL     Error if attempting to create existing file

   These flags are set using the bitwise OR operator (|)  to
   separate specified flags.

   Opening a file with O_APPEND causes each write on the file to
   be appended to the end. (In contrast, with the VAX C RTL the
   behavior of files opened in append mode was to start at EOF and,
   thereafter, write at the current file position.)

   If O_TRUNC is specified and the file exists, open creates a new
   file by incrementing the version number by 1, leaving the old
   version in existence.

   If O_CREAT is set and the named file does not exist, the C RTL
   creates it with any attributes specified in the fourth and
   subsequent arguments ( . . . ). If O_EXCL is set with O_CREAT and
   the named file exists, the attempted open returns an error.
 

mode

   An unsigned value that specifies the file-protection mode. The
   compiler performs a bitwise AND operation on the mode and the
   complement of the current protection mode.

   You can construct modes by using the bitwise OR operator (|)  to
   separate specified modes. The modes are:

   0400   OWNER:READ
   0200   OWNER:WRITE
   0100   OWNER:EXECUTE
   0040   GROUP:READ
   0020   GROUP:WRITE
   0010   GROUP:EXECUTE
   0004   WORLD:READ
   0002   WORLD:WRITE
   0001   WORLD:EXECUTE

   The system is given the same access privileges as the owner. A
   WRITE privilege also implies a DELETE privilege.
 

 . . .

   Optional file attribute arguments. The file attribute arguments
   are the same as those used in the creat function. For more
   information, see the creat function.