fcntl.5 (2010 09)

f
fcntl(5) fcntl(5)
NAME
fcntl - file control options
SYNOPSIS
#include <sys/types.h>
#include <fcntl.h>
DESCRIPTION
The fcntl() function provides for control over open files. The
<fcntl.h> include file describes
requests and arguments to
fcntl() and open()
. See fcntl (2) and open (2).
The access modes set by
open() and accessed by
fcntl() are:
O_RDONLY
O_WRONLY
O_RDWR
The mask for file access modes is:
O_ACCMODE
The file status flags set by
open() or fcntl() and accessed by fcntl() are:
O_NDELAY Nonblocking I/O.
O_NONBLOCK POSIX-style nonblocking I/O.
O_APPEND Append (writes guaranteed at the end).
O_DSYNC Write through cache for data.
O_SYNC Write through cache for data and attributes.
O_RSYNC|O_DSYNC Write through cache for data on reads and writes.
O_RSYNC|O_SYNC Write through cache for data and attributes on reads and writes.
O_LARGEFILE When the filesystem is mounted as large files enabled, the O_LARGEFILE
option allows the file to grow over 2 GB.
The flag
O_SYNCIO is a synonym for O_SYNC and is defined for backward compatibility in
<fcntl.h>.
The flag values accessible only to
open() are:
O_CREAT Open with file create (uses third open arg).
O_TRUNC Open with truncation.
O_EXCL Exclusive open.
O_NOCTTY Do not assign a controlling terminal.
O_NOFOLLOW Do not traverse a symbolic link if it is the last component in the path.
The requests for
fcntl() are:
F_DUPFD Duplicate file descriptor.
F_GETFD Get file descriptor flags.
F_SETFD Set file descriptor flags.
F_GETFL Get file flags.
F_SETFL Set file flags.
F_GETLK Get blocking file lock.
F_SETLK Set or clear file locks and fail on busy.
F_SETLKW Set or clear file locks and wait on busy.
F_ADVISE Fadvise service request (see fadvise (2)).
The file descriptor flag for
F_GETFD, F_SETFD is:
FD_CLOEXEC
The file segment locking control structure struct flock, includes the following members:
short l_type; /* F_RDLCK, F_WRLCK or F_UNLCK */
short l_whence; /* Flag - see lseek(2) */
off_t l_start; /* Relative offset in bytes */
off_t l_len; /* Size; if 0 then until EOF */
pid_t l_pid; /* By F_GETLK - process holding lock */
The file segment locking types are:
F_RDLCK Read lock.
F_WRLCK Write lock.
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1