| 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
Description
POSIX miscellaneous stuff, mostly from unistd.h
System environment
getSystemID :: IO SystemID #
Sleeping
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.
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 () #
Sleep for the specified duration (in nanoseconds)
GHC Note: the comment for usleep also applies here.
File synchronisation
fileSynchronise :: Fd -> IO () #
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 () #
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