A file is opened or created by calling the open function.

int open (const char *pathname, int oflag, .../*,mode_t mode */);

 The pathname is the name of the file to open or create. There are a multiple options for this function, which are apecified by the oflag argument. This argument formed by OR'ing together one or more of the following constants (from <fcntl.h>) 

O_RDONLY Open for reading only,

O_WRONLY Open for writing only,

O_RDWR Open for reading and writing,

Optional:

O_APPEND, O_CREAT, O_EXCL, O_TRUNC, O_NOCTTY, O_NONBLOCK, O_SYNC

Zaheer Anjum Kazi 203.109.65.3 07:25, 3 November 2005 (UTC)

Reference: Advanced Unix Programming in the UNIX Environment W. Richard Stevens ISBN 81-7808-096-6