fcntl(M)

fcntl(M)
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:

ISO/IEC 9945-1:1990, Information technology - Portable Operating System Interface (POSIX) - Part 1: System Application Program Interface (API) [C Language] (IEEE Std 1003.1-1990);
AT&T SVID Issue 2;
X/Open CAE Specification, System Interfaces and Headers, Issue 4, 1992.

SCO OpenServer Release 5.0.6 -- 1 August 2000