System.Posix.User

# User environment

## Querying the user environment

getRealUserID
getRealGroupID
getEffectiveUserID
getEffectiveGroupID
getGroups
getLoginName
getEffectiveUserName

### The group database

data GroupEntry
getGroupEntryForID
getGroupEntryForName
getAllGroupEntries

### The user database

data UserEntry
getUserEntryForID
getUserEntryForName
getAllUserEntries

## Modifying the user environment

setUserID
setGroupID