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 139
```
INT2NUM(FD_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 78
```
INT2NUM(F_DUPFD)
```
F_GETFD =

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

# File 'ext/fcntl/fcntl.c', line 85
```
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 108
```
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 93
```
INT2NUM(F_GETLK)
```
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 100
```
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 116
```
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 124
```
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 132
```
INT2NUM(F_SETLKW)
```
F_UNLCK =

Remove lock for a region of a file

# File 'ext/fcntl/fcntl.c', line 153
```
INT2NUM(F_UNLCK)
```
F_WRLCK =

Write lock for a region of a file

# File 'ext/fcntl/fcntl.c', line 160
```
INT2NUM(F_WRLCK)
```
O_ACCMODE =

Mask to extract the read/write flags

# File 'ext/fcntl/fcntl.c', line 237
```
INT2FIX(O_ACCMODE)
```
O_APPEND =

Open the file in append mode

# File 'ext/fcntl/fcntl.c', line 195
```
INT2NUM(O_APPEND)
```
O_CREAT =

Create the file if it doesn’t exist

# File 'ext/fcntl/fcntl.c', line 167
```
INT2NUM(O_CREAT)
```
O_EXCL =

Used with O_CREAT, fail if the file exists

# File 'ext/fcntl/fcntl.c', line 174
```
INT2NUM(O_EXCL)
```
O_NDELAY =

Open the file in non-blocking mode

# File 'ext/fcntl/fcntl.c', line 209
```
INT2NUM(O_NDELAY)
```
O_NOCTTY =

Open TTY without it becoming the controlling TTY

# File 'ext/fcntl/fcntl.c', line 181
```
INT2NUM(O_NOCTTY)
```
O_NONBLOCK =

Open the file in non-blocking mode

# File 'ext/fcntl/fcntl.c', line 202
```
INT2NUM(O_NONBLOCK)
```
O_RDONLY =

Open the file in read-only mode

# File 'ext/fcntl/fcntl.c', line 216
```
INT2NUM(O_RDONLY)
```
O_RDWR =

Open the file in read-write mode

# File 'ext/fcntl/fcntl.c', line 223
```
INT2NUM(O_RDWR)
```
O_TRUNC =

Truncate the file on open

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

Open the file in write-only mode.

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