FCNTL(M)                             UNIX System V



     Name
          fcntl - file control options


     Syntax
          #include <fcntl.h>


     Description
          The fcntl(S) function provides for control over open  files.
          This  include file describes requests and arguments to fcntl
          and open(S).

          /* Flag values accessible to open(S) and fcntl(S) */
          /*  (The first three can only be set by open) */
          #define O_RDONLY 0
          #define O_WRONLY 1
          #define O_RDWR   2
          #define O_NDELAY 04      /* Non-blocking I/O */
          #define O_APPEND 010     /* append (writes guaranteed at the end) */
          #define O_SYNC   020     /* synchronous write option */

          /* Flag values accessible only to open(S) */
          #define O_CREAT  00400   /* open with file create (uses third open arg)*/
          #define O_TRUNC  01000   /* open with truncation */
          #define O_EXCL   02000   /* exclusive open */

          /* fcntl(S) requests */
          #define F_DUPFD  0       /* Duplicate fildes */
          #define F_GETFD  1       /* Get fildes flags */
          #define F_SETFD  2       /* Set fildes flags */
          #define F_GETFL  3       /* Get file flags */
          #define F_SETFL  4       /* Set file flags */
          #define F_GETLK  5       /* Get file lock */
          #define F_SETLK  6       /* Set file lock */
          #define F_SETLKW 7       /* Set file lock and wait */
          #define F_CHKFL  8       /* Check legality of file flag changes */

          /* file segment locking control structure */
          struct flock {
                short l_type;
                short l_whence;
                long  l_start;
                long  l_len;      /* if 0 then until EOF */
                short l_sysid;    /* returned with F_GETLK*/
                short l_pid;      /* returned with F_GETLK*/
          }

          /* file segment locking types */
          #define F_RDLCK 01   /* Read lock */
          #define F_WRLCK 02   /* Write lock */
          #define F_UNLCK 03   /* Remove locks */



     See Also
          fcntl(S), open(S)


     Standards Conformance
          fcntl is conformant with:
          AT&T SVID Issue 2, Select Code 307-127;
          and The X/Open Portability Guide II of January 1987.


     (printed 2/15/90)                                   FCNTL(M)