GETENV$.html -- ACL2 Version 6.3

### GETENV$

read an environment variable

    Major Section:  ACL2-BUILT-INS

`(Getenv$ str state)`, where `str` is a string, reads the value of environment variable `str`, returning a value of `nil` if none is found or if the read fails. The logical story is that `getenv$` reads its value from the `oracle` field of the ACL2 `state`. The return value is thus a triple of the form `(mv erp val state)`, where `erp` will always be `nil` in practice, and logically, `val` is the top of the acl2-oracle field of the state and the returned state has the updated (popped) acl2-oracle.

    Example:
    (getenv$ "PWD" state) ==> (mv nil "/u/joe/work" state)

Also see setenv$.