The UnixEnv structure

The UnixEnv structure supports operations on the host process’s environment, which is essentially a list of strings of the form “`name=value`”, where the “=” character does not appear in name. We assume that environments are "well formed;" i.e., that an environment variable is only defined once.

Warning

Binding the user’s environment as an SML value and then exporting the SML heap image can result in incorrect behavior, since the environment bound in the heap image may differ from the user’s environment when the exported heap image is loaded.

Synopsis

signature UNIX_ENV
structure UnixEnv : UNIX_ENV

Interface

val getFromEnv : (string * string list) -> string option

val getValue : {name : string, default : string, env : string list} -> string

val removeFromEnv : (string * string list) -> string list

val addToEnv : (string * string list) -> string list

val environ : unit -> string list

val getEnv : string -> string option

Description

val getFromEnv : (string * string list) -> string option

getEnv (name, env) returns SOME v if (name, v) is in the environment env. Otherwise, it returns NONE if name is not bound in env.

val getValue : {name : string, default : string, env : string list} -> string

getEnv {name, default, env} returns v if (name, v) is in the environment env. Otherwise, it returns default if name is not bound in env.

val removeFromEnv : (string * string list) -> string list

removeFromEnv (name, env) removes any binding of name from the environment. Note that if env has multiple bindings of name (i.e., env is not well formed), then only the first binding is removed.

val addToEnv : (string * string list) -> string list

addToEnv (bind, env) adds the binding bind, which should be of the form “`name=value`”, to the environment. If there was an existing binding of name in env, then it will be replaced.

val environ : unit -> string list

env () returns the user’s (host process) environment.

val getEnv : string -> string option

getEnv name returns the binding of the environment variable name in the user’s (host process) environment.

See Also

The Unix Library