fcntl(5)                                                 fcntl(5)



NAME
     fcntl - file control options

SYNOPSIS
     #include <fcntl.h>

DESCRIPTION
     fcntl(2) provides for control over open files.  The include
     file describes requests and arguments to fcntl(2) and
     open(2).

        #ifndef __fcntl_h
        #define __fcntl_h

        /* POSIX requires types; most applications don't do this yet! */
        #ifndef __sys_types_h
        #include <sys/types.h>
        #endif /* !__sys_types_h */

        /* Flag values accessible to open(2) and fcntl(2) */
        /*  (The first three can only be set by open) */
        #if defined(_SYSV_SOURCE) || defined(_POSIX_SOURCE)
        #ifndef __sys_file_h
        #define   O_RDONLY  0
        #define   O_WRONLY  1
        #define   O_RDWR    2
        #define   O_APPEND  010  /* append (writes
                                         guaranteed at the end) */

        /* Flag values accessible only to open(2) */
        #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(2) 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 */

        /* file segment locking set data type - information passed */
        /* to system by user */
        struct flock {
             short     l_type;
             short     l_whence;
             long l_start;
             long l_len;    /* len = 0 means until end of file */



January 1992                                                    1

fcntl(5)                                                 fcntl(5)



             int  l_pid;
        };

        /* file segment locking types */
        #define   F_RDLCK   01   /* Read lock */
        #define   F_WRLCK   02   /* Write lock */
        #define   F_UNLCK   03   /* Remove locks */

        #endif /* _SYSV_SOURCE || _POSIX_SOURCE */

        #ifdef _BSD_SOURCE
        /* Additional fcntl(2) request */
        #define F_GETOWN    8    /* Get owner */
        #define F_SETOWN    9    /* Set owner */
        #endif /* _BSD_SOURCE */

        #ifdef _POSIX_SOURCE
        /* File access mode mask */
        #define 0_ACCMODE   03

        /* POSIX-defined argument to F_SETFD */
        #define FD_CLOEXEC  0x0001

        /* POSIX-defined flag values accesible to open(2) and/or fcntl(2) */
        #define 0_NONBLOCK   040000    /* 0_NDELAY POSIX style */
        #define 0_NOCTTY    0l00000  /* don't assign controlling tty */
        #endif  /* _POSIX_SOURCE */

        #ifdef _AUX_SOURCE
        /* Implementation-define flag values accessible to open(2) */
        #define O_GETCTTY   0200000     /* force controlling tty assignment */
        #endif /* _AUX_SOURCE */
        #endif /* !__fcntl_h */


SEE ALSO
     fcntl(2), open(2)


















2                                                    January 1992