Copyright	(c) The University of Glasgow 2002
License	BSD-style (see the file libraries/base/LICENSE)
Maintainer	libraries@haskell.org
Stability	provisional
Portability	non-portable (requires POSIX)
Safe Haskell	Safe
Language	Haskell2010

System.Posix.Unistd

Contents

System environment
Sleeping
File synchronisation

Description

POSIX miscellaneous stuff, mostly from unistd.h

Synopsis

data SystemID = SystemID {
- systemName :: String
- nodeName :: String
- release :: String
- version :: String
- machine :: String
}
getSystemID :: IO SystemID
data SysVar
- = ArgumentLimit
- | ChildLimit
- | ClockTick
- | GroupLimit
- | OpenFileLimit
- | PosixVersion
- | HasSavedIDs
- | HasJobControl
getSysVar :: SysVar -> IO Integer
sleep :: Int -> IO Int
usleep :: Int -> IO ()
nanosleep :: Integer -> IO ()
fileSynchronise :: Fd -> IO ()
fileSynchroniseDataOnly :: Fd -> IO ()

System environment

data SystemID Source #

Constructors

SystemID
Fields systemName :: String nodeName :: String release :: String version :: String machine :: String

getSystemID :: IO SystemID Source #

data SysVar Source #

Constructors

ArgumentLimit
ChildLimit
ClockTick
GroupLimit
OpenFileLimit
PosixVersion
HasSavedIDs
HasJobControl

getSysVar :: SysVar -> IO Integer Source #

Sleeping

sleep :: Int -> IO Int Source #

Warning: This function has several shortcomings (see documentation). Please consider using Control.Concurrent.threadDelay instead.

Sleep for the specified duration (in seconds). Returns the time remaining (if the sleep was interrupted by a signal, for example).

GHC Note: threadDelay is a better choice. Since GHC uses signals for its internal clock, a call to sleep will usually be interrupted immediately. That makes sleep unusable in a program compiled with GHC, unless the RTS timer is disabled (with +RTS -V0). Furthermore, without the -threaded option, sleep will block all other user threads. Even with the -threaded option, sleep requires a full OS thread to itself. threadDelay has none of these shortcomings.

usleep :: Int -> IO () Source #

Sleep for the specified duration (in microseconds).

GHC Note: threadDelay is a better choice. Without the -threaded option, usleep will block all other user threads. Even with the -threaded option, usleep requires a full OS thread to itself. threadDelay has neither of these shortcomings.

nanosleep :: Integer -> IO () Source #

Sleep for the specified duration (in nanoseconds)

GHC Note: the comment for usleep also applies here.

File synchronisation

fileSynchronise :: Fd -> IO () Source #

Performs fsync(2) operation on file-descriptor.

Throws IOError ("unsupported operation") if platform does not provide fsync(2) (use #if HAVE_FSYNC CPP guard to detect availability).

Since: unix-2.7.1.0

fileSynchroniseDataOnly :: Fd -> IO () Source #

Warning: operation will throw IOError "unsupported operation" (CPP guard: #if HAVE_FDATASYNC)

Performs fdatasync(2) operation on file-descriptor.

Throws IOError ("unsupported operation") if platform does not provide fdatasync(2) (use #if HAVE_FDATASYNC CPP guard to detect availability).

Since: unix-2.7.1.0