Fcntl loads the constants defined in the system‘s <fcntl.h> C header file, and used with both the fcntl(2) and open(2) POSIX system calls.

Copyright (C) 1997-2001 Yukihiro Matsumoto

Documented by mathew <meta@pobox.com>

Usage

To perform a fcntl(2) operation, use IO::fcntl in the core classes.

To perform an open(2) operation, use IO::sysopen.

The set of operations and constants available depends upon specific OS platform. Some values listed below may not be supported on your system.

The constants supported by Ruby for use with IO::fcntl are:

• F_DUPFD - duplicate a close-on-exec file handle to a non-close-on-exec file handle.
• F_GETFD - read the close-on-exec flag of a file handle.
• F_SETFD - set the close-on-exec flag of a file handle.
• FD_CLOEXEC - the value of the close-on-exec flag.
• F_GETFL - get file descriptor flags.
• F_SETFL - set file descriptor flags.
• O_APPEND, O_NONBLOCK, etc (see below) - file descriptor flag values for the above.
• F_GETLK - determine whether a given region of a file is locked.
• F_SETLK - acquire a lock on a region of a file.
• F_SETLKW - acquire a lock on a region of a file, waiting if necessary.
• F_RDLCK, F_WRLCK, F_UNLCK - types of lock for the above.

The constants supported by Ruby for use with IO::sysopen are:

• O_APPEND - open file in append mode.
• O_NOCTTY - open tty without it becoming controlling tty.
• O_CREAT - create file if it doesn‘t exist.
• O_EXCL - used with O_CREAT, fail if file exists.
• O_TRUNC - truncate file on open.
• O_NONBLOCK / O_NDELAY - open in non-blocking mode.
• O_RDONLY - open read-only.
• O_WRONLY - open write-only.
• O_RDWR - open read-write.
• O_ACCMODE - mask to extract read/write flags.

Example:

  require 'fcntl'

  fd = IO::sysopen('/tmp/tempfile',
       Fcntl::O_WRONLY | Fcntl::O_EXCL | Fcntl::O_CREAT)
  f = IO.open(fd)
  f.syswrite("TEMP DATA")
  f.close