| 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 | Trustworthy | 
| Language | Haskell2010 | 
System.Posix.Env.ByteString
Description
POSIX environment support
Synopsis
- getEnv :: ByteString -> IO (Maybe ByteString)
- getEnvDefault :: ByteString -> ByteString -> IO ByteString
- getEnvironmentPrim :: IO [ByteString]
- getEnvironment :: IO [(ByteString, ByteString)]
- putEnv :: ByteString -> IO ()
- setEnv :: ByteString -> ByteString -> Bool -> IO ()
- unsetEnv :: ByteString -> IO ()
- getArgs :: IO [ByteString]
Environment Variables
Arguments
| :: ByteString | variable name | 
| -> IO (Maybe ByteString) | variable value | 
getEnv looks up a variable in the environment.
Arguments
| :: ByteString | variable name | 
| -> ByteString | fallback value | 
| -> IO ByteString | variable value or fallback value | 
getEnvDefault is a wrapper around getEnv where the
 programmer can specify a fallback if the variable is not found
 in the environment.
getEnvironmentPrim :: IO [ByteString] #
Arguments
| :: IO [(ByteString, ByteString)] | [(key,value)] | 
getEnvironment retrieves the entire environment as a
 list of (key,value) pairs.
Arguments
| :: ByteString | "key=value" | 
| -> IO () | 
putEnv function takes an argument of the form name=value
 and is equivalent to setEnv(key,value,True{-overwrite-}).
Arguments
| :: ByteString | variable name | 
| -> ByteString | variable value | 
| -> Bool | overwrite | 
| -> IO () | 
The setEnv function inserts or resets the environment variable name in
     the current environment list.  If the variable name does not exist in the
     list, it is inserted with the given value.  If the variable does exist,
     the argument overwrite is tested; if overwrite is False, the variable is
     not reset, otherwise it is reset to the given value.
Arguments
| :: ByteString | variable name | 
| -> IO () | 
The unsetEnv function deletes all instances of the variable name
 from the environment.
Program arguments
getArgs :: IO [ByteString] #
Computation getArgs returns a list of the program's command
 line arguments (not including the program name), as ByteStrings.
Unlike getArgs, this function does no Unicode
 decoding of the arguments; you get the exact bytes that were passed
 to the program by the OS.  To interpret the arguments as text, some
 Unicode decoding should be applied.