fcntl(M)

Syntax

Description

/ 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

Standards conformance

ISO/IEC 99451:1990, Information technology Portable Operating System Interface (POSIX) Part 1: System Application Program Interface (API) [C Language] (IEEE Std 1003.11990);
AT&T SVID Issue 2;
X/Open CAE Specification, System Interfaces and Headers, Issue 4, 1992.