module Fcntl
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.
To perform a fcntl(2) operation, use IO::fcntl.
To perform an open(2) operation, use IO::sysopen
.
The set of operations and constants available depends upon specific operating system. Some values listed below may not be supported on your system.
See your fcntl(2) man page for complete details.
Open /tmp/tempfile as a write-only file that is created if it doesn’t exist:
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
Get the flags on file s
:
m = s.fcntl(Fcntl::F_GETFL, 0)
Set
the non-blocking flag on f
in addition to the existing flags in m
.
f.fcntl(Fcntl::F_SETFL, Fcntl::O_NONBLOCK|m)
Constants
- FD_CLOEXEC
the value of the close-on-exec flag.
- F_DUP2FD
It is a FreeBSD specific constant and equivalent to dup2 call.
- F_DUP2FD_CLOEXEC
It is a FreeBSD specific constant and acts similarly as
F_DUP2FD
but set theFD_CLOEXEC
flag in addition.- F_DUPFD
Duplicate a file descriptor to the minimum unused file descriptor greater than or equal to the argument.
The close-on-exec flag of the duplicated file descriptor is set. (Ruby uses F_DUPFD_CLOEXEC internally if available to avoid race condition.
F_SETFD
is used if F_DUPFD_CLOEXEC is not available.)- F_GETFD
Read the close-on-exec flag of a file descriptor.
- F_GETFL
Get the file descriptor flags. This will be one or more of the O_* flags.
- F_GETLK
Determine whether a given region of a file is locked. This uses one of the F_*LK flags.
- F_GETPIPE_SZ
Return (as the function result) the capacity of the pipe referred to by fd.
- F_RDLCK
Read lock for a region of a file
- F_SETFD
Set
the close-on-exec flag of a file descriptor.- F_SETFL
Set
the file descriptor flags. This will be one or more of the O_* flags.- F_SETLK
Acquire a lock on a region of a file. This uses one of the F_*LCK flags.
- F_SETLKW
Acquire a lock on a region of a file, waiting if necessary. This uses one of the F_*LCK flags
- F_SETPIPE_SZ
Change the capacity of the pipe referred to by fd to be at least arg bytes.
- F_UNLCK
Remove lock for a region of a file
- F_WRLCK
Write lock for a region of a file
- O_ACCMODE
Mask to extract the read/write flags
- O_APPEND
Open the file in append mode
- O_CREAT
Create the file if it doesn’t exist
- O_EXCL
Used with
O_CREAT
, fail if the file exists- O_NDELAY
Open the file in non-blocking mode
- O_NOCTTY
Open TTY without it becoming the controlling TTY
- O_NONBLOCK
Open the file in non-blocking mode
- O_RDONLY
Open the file in read-only mode
- O_RDWR
Open the file in read-write mode
- O_TRUNC
Truncate the file on open
- O_WRONLY
Open the file in write-only mode.
- VERSION
The version string.