#  File src/library/base/R/getenv.R
#  Part of the R package, https://www.R-project.org
#
#  Copyright (C) 1995-2014 The R Core Team
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  A copy of the GNU General Public License is available at
#  https://www.R-project.org/Licenses/

Sys.getenv <- function(x = NULL, unset = "", names = NA)
{
    if (is.null(x)) {
        ## This presumes that '=' does not appear as part of the name
        ## of an environment variable.  That used to happen on Windows.
        x <- .Internal(Sys.getenv(character(), ""))
        m <- regexpr("=", x, fixed = TRUE)
        n <- substring(x, 1L, m - 1L)
        v <- substring(x, m + 1L)
	if (isFALSE(names))
	    v[sort.list(n)]
	else { # with names
	    v <- structure(v, names = n)
	    structure(class = "Dlist", # with nice print method
		      v[sort.list(n)])
	}
    } else {
        v <- .Internal(Sys.getenv(as.character(x), as.character(unset)))
	if (isTRUE(names) || (length(x) > 1L && !isFALSE(names)))
            structure(v, names = x)
        else v
    }
}

Sys.setenv <- function(...)
{
    nm <- ...names()
    if(is.null(nm) || "" %in% nm)
        stop("all arguments must be named")
    .Internal(Sys.setenv(nm, as.character(unlist(list(...)))))
}

Sys.unsetenv <- function(x) .Internal(Sys.unsetenv(as.character(x)))

Sys.getpid <- function() .Internal(Sys.getpid())
