Module: Fcntl

Relationships & Source Files
Defined in:	ext/fcntl/fcntl.c

Overview

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)

Constant Summary

FD_CLOEXEC =

the value of the close-on-exec flag.

# File 'ext/fcntl/fcntl.c', line 140
```
INT2NUM(FD_CLOEXEC)
```
F_ALLOCATEALL =

macOS specific flag used with F_PREALLOCATE for allocating all contiguous space or no space.

# File 'ext/fcntl/fcntl.c', line 275
```
INT2NUM(F_ALLOCATEALL)
```
F_ALLOCATECONTIG =

macOS specific flag used with F_PREALLOCATE for allocating contiguous space.

# File 'ext/fcntl/fcntl.c', line 267
```
INT2NUM(F_ALLOCATECONTIG)
```
F_ALLOCATEPERSIST =

macOS specific flag used with F_PREALLOCATE. Allocate space that is not freed when close is called.

# File 'ext/fcntl/fcntl.c', line 283
```
INT2NUM(F_ALLOCATEPERSIST)
```
F_DUP2FD =

It is a FreeBSD specific constant and equivalent to dup2 call.

# File 'ext/fcntl/fcntl.c', line 244
```
INT2NUM(F_DUP2FD)
```
F_DUP2FD_CLOEXEC =

It is a FreeBSD specific constant and acts similarly as F_DUP2FD but set the FD_CLOEXEC flag in addition.

# File 'ext/fcntl/fcntl.c', line 252
```
INT2NUM(F_DUP2FD_CLOEXEC)
```
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.)

# File 'ext/fcntl/fcntl.c', line 87
```
INT2NUM(F_DUPFD)
```
F_GETFD =

Read the close-on-exec flag of a file descriptor.

# File 'ext/fcntl/fcntl.c', line 93
```
INT2NUM(F_GETFD)
```
F_GETFL =

Get the file descriptor flags. This will be one or more of the O_* flags.

# File 'ext/fcntl/fcntl.c', line 113
```
INT2NUM(F_GETFL)
```
F_GETLK =

Determine whether a given region of a file is locked. This uses one of the F_*LK flags.

# File 'ext/fcntl/fcntl.c', line 100
```
INT2NUM(F_GETLK)
```
F_GETPIPE_SZ =

Return (as the function result) the capacity of the pipe referred to by fd.

# File 'ext/fcntl/fcntl.c', line 170
```
INT2NUM(F_GETPIPE_SZ)
```
F_PEOFPOSMODE =

macOS specific flag used with F_PREALLOCATE. Allocate from the physical end of file

# File 'ext/fcntl/fcntl.c', line 291
```
INT2NUM(F_PEOFPOSMODE)
```
F_PREALLOCATE =

macOS specific flag used for preallocating file space.

# File 'ext/fcntl/fcntl.c', line 259
```
INT2NUM(F_PREALLOCATE)
```
F_RDLCK =

Read lock for a region of a file

# File 'ext/fcntl/fcntl.c', line 146
```
INT2NUM(F_RDLCK)
```
F_SETFD =

Set the close-on-exec flag of a file descriptor.

# File 'ext/fcntl/fcntl.c', line 106
```
INT2NUM(F_SETFD)
```
F_SETFL =

Set the file descriptor flags. This will be one or more of the O_* flags.

# File 'ext/fcntl/fcntl.c', line 120
```
INT2NUM(F_SETFL)
```
F_SETLK =

Acquire a lock on a region of a file. This uses one of the F_*LCK flags.

# File 'ext/fcntl/fcntl.c', line 127
```
INT2NUM(F_SETLK)
```
F_SETLKW =

Acquire a lock on a region of a file, waiting if necessary. This uses one of the F_*LCK flags

# File 'ext/fcntl/fcntl.c', line 134
```
INT2NUM(F_SETLKW)
```
F_SETPIPE_SZ =

Change the capacity of the pipe referred to by fd to be at least arg bytes.

# File 'ext/fcntl/fcntl.c', line 164
```
INT2NUM(F_SETPIPE_SZ)
```
F_UNLCK =

Remove lock for a region of a file

# File 'ext/fcntl/fcntl.c', line 152
```
INT2NUM(F_UNLCK)
```
F_VOLPOSMODE =

macOS specific flag used with F_PREALLOCATE. Allocate from the volume offset.

# File 'ext/fcntl/fcntl.c', line 298
```
INT2NUM(F_VOLPOSMODE)
```
F_WRLCK =

Write lock for a region of a file

# File 'ext/fcntl/fcntl.c', line 158
```
INT2NUM(F_WRLCK)
```
O_ACCMODE =

Mask to extract the read/write flags

# File 'ext/fcntl/fcntl.c', line 238
```
INT2FIX(O_ACCMODE)
```
O_APPEND =

Open the file in append mode

# File 'ext/fcntl/fcntl.c', line 200
```
INT2NUM(O_APPEND)
```
O_CREAT =

Create the file if it doesn’t exist

# File 'ext/fcntl/fcntl.c', line 176
```
INT2NUM(O_CREAT)
```
O_EXCL =

Used with O_CREAT, fail if the file exists

# File 'ext/fcntl/fcntl.c', line 182
```
INT2NUM(O_EXCL)
```
O_NDELAY =

Open the file in non-blocking mode

# File 'ext/fcntl/fcntl.c', line 212
```
INT2NUM(O_NDELAY)
```
O_NOCTTY =

Open TTY without it becoming the controlling TTY

# File 'ext/fcntl/fcntl.c', line 188
```
INT2NUM(O_NOCTTY)
```
O_NONBLOCK =

Open the file in non-blocking mode

# File 'ext/fcntl/fcntl.c', line 206
```
INT2NUM(O_NONBLOCK)
```
O_RDONLY =

Open the file in read-only mode

# File 'ext/fcntl/fcntl.c', line 218
```
INT2NUM(O_RDONLY)
```
O_RDWR =

Open the file in read-write mode

# File 'ext/fcntl/fcntl.c', line 224
```
INT2NUM(O_RDWR)
```
O_TRUNC =

Truncate the file on open

# File 'ext/fcntl/fcntl.c', line 194
```
INT2NUM(O_TRUNC)
```
O_WRONLY =

Open the file in write-only mode.

# File 'ext/fcntl/fcntl.c', line 230
```
INT2NUM(O_WRONLY)
```
VERSION =

The version string.

# File 'ext/fcntl/fcntl.c', line 76
```
rb_str_new_cstr(FCNTL_VERSION)
```