FCNTL(5-SVR4)       RISC/os Reference Manual        FCNTL(5-SVR4)



NAME
     fcntl - file control options

SYNOPSIS
     #include <fcntl.h>

DESCRIPTION
     The <fcntl.h> header defines the following requests and
     arguments for use by the functions fcntl [see fcntl(2)] and
     open [see open(2)].

        Values for cmd used by fcntl (the following values are unique):
             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_GETLK        Get record locking information
             F_SETLK        Set record locking information
             F_SETLKW       Set record locking information;
                            wait if blocked

        File descriptor flags used for fcntl:
             FD_CLOEXEC     Close the file descriptor upon
                            execution of an exec function [see exec(2)]

        Values for l_type used for record locking with fcntl
        (the following values are unique):
             F_RDLCK        Shared or read lock
             F_UNLCK        Unlock
             F_WRLCK        Exclusive or write lock

        The following three sets of values are bitwise distinct:
        Values for oflag used by open:
             O_CREAT        Create file if it does not exist
             O_EXCL         Exclusive use flag
             O_NOCTTY       Do not assign controlling tty
             O_TRUNC        Truncate flag

        File status flags used for open and fcntl:
             O_APPEND       Set append mode
             O_NDELAY       Non-blocking mode
             O_NONBLOCK     Non-blocking mode (POSIX)
             O_SYNC         Synchronous writes

        Mask for use with file access modes:
             O_ACCMODE      Mask for file access modes








                        Printed 11/19/92                   Page 1

FCNTL(5-SVR4)       RISC/os Reference Manual        FCNTL(5-SVR4)




        File access modes used for open and fcntl:
             O_RDONLY       Open for reading only
             O_RDWR         Open for reading and writing
             O_WRONLY       Open for writing only

     The structure flock describes a file lock.  It includes the
     following members:

          short       l_type;/* Type of lock */
          short       l_whence;/* Flag for starting offset */
          off_t       l_start;/* Relative offset in bytes */
          off_t       l_len;/* Size; if 0 then until EOF */
          long l_sysid;  /* Returned with F_GETLK */
          pid_t       l_pid;/* Returned with F_GETLK */

SEE ALSO
     creat(2), exec(2), fcntl(2), open(2).





































 Page 2                 Printed 11/19/92