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.