unix- POSIX functionality

Copyright(c) The University of Glasgow 2002
LicenseBSD-style (see the file libraries/base/LICENSE)
Portabilitynon-portable (requires POSIX)
Safe HaskellSafe



POSIX environment support



getEnv :: String -> IO (Maybe String) Source

getEnv looks up a variable in the environment.

getEnvDefault :: String -> String -> IO String Source

getEnvDefault is a wrapper around getEnv where the programmer can specify a fallback if the variable is not found in the environment.

getEnvironment :: IO [(String, String)] Source

getEnvironment retrieves the entire environment as a list of (key,value) pairs.

setEnvironment :: [(String, String)] -> IO () Source

setEnvironment resets the entire environment to the given list of (key,value) pairs.

putEnv :: String -> IO () Source

putEnv function takes an argument of the form name=value and is equivalent to setEnv(key,value,True{-overwrite-}).

setEnv :: String -> String -> Bool -> IO () Source

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.

unsetEnv :: String -> IO () Source

The unsetEnv function deletes all instances of the variable name from the environment.

clearEnv :: IO () Source

The clearEnv function clears the environment of all name-value pairs.