fcntl(5)
NAME
fcntl − file control options
SYNOPSIS
#include <sys/fcntl.h>
DESCRIPTION
The fcntl(2) function provides for control over open files. The include file describes requests and arguments to fcntl and open(2).
Flag values accessible to open(2) and fcntl(2) (The first three can only
be set by open):
| O_RDONLY | Open for reading only |
| O_WRONLY | Open for writing only |
| O_RDWR | Open for reading and writing |
| O_NDELAY | No delay |
| O_APPEND | append (writes guaranteed at the end) |
| O_SYNC | synchronous write option |
| O_NONBLOCK | Non-blocking I/O |
Flag values accessible only to open(2):
| O_CREAT | open with file create (uses 3rd open arg) |
| O_TRUNC | open with truncation |
| O_EXCL | exclusive open |
| O_DIRECT | direct I/O (regular disk files) |
| O_OCTTY | Don’t assign a controlling terminal |
fcntl(2) requests:
| F_DUPFD | Duplicate file descriptor |
| F_GETFD | Get file descriptor flags |
| F_SETFD | Set file descriptor flags |
| F_GETFL | Get file status flags |
| F_SETFL | Set file status flags |
| F_CHKFL | Check validity of file status flag argument |
| F_GETLK | Get record locking information |
| F_SETLK | Set or clear file locks and fail on busy |
| F_SETLKW | Set or clear file locks and wait on busy |
| F_FREESP | Free storage in file |
| F_GETOWN | Get owner |
| F_SETOWN | Set owner |
| F_GETASYNC | Get ability to perform asynchronous I/O |
| F_EXTSIZE | Allocate contiguous space to disk file |
flock structure fields:
| short | l_type | |
| short | l_whence | |
| off_t | l_start | |
| off_t | l_len | |
| pid_t | l_pid |
File segment locking types:
| F_RDLCK | Read lock |
| F_WRLCK | Write lock |
| F_UNLCK | Remove locks |
SEE ALSO
CX/UX Programmer’s Reference Manual