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[bpt/emacs.git] / lisp / env.el

;;; setenv.el --- functions to manipulate environment variables.

;; Maintainer: FSF
;; Last-Modified: 16 Mar 1992
;; Keywords: extensions

;;; Copyright Free Software Foundation 1991

;;; This file is part of GNU Emacs.

;;; GNU Emacs 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, or (at your option)
;;; any later version.

;;; GNU Emacs 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.

;;; You should have received a copy of the GNU General Public License
;;; along with GNU Emacs; see the file COPYING.  If not, write to
;;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

;;; Code:

(defun setenv (variable value)
  "Set the value of the environment variable named VARIABLE to VALUE.
VARIABLE and VALUE should both be strings.
This function works by modifying process-environment."
  (if (string-match "=" variable)
      (error "name of environment variable contains an '=' character")
    (let ((pattern (concat "^" (regexp-quote (concat variable "="))))
	  (scan process-environment))
      (while scan
	(cond
	 ((string-match pattern (car scan))
	  (setcar scan (concat variable "=" value))
	  (setq scan nil))
	 ((null (setq scan (cdr scan)))
	  (setq process-environment
		(cons (concat variable "=" value) process-environment))))))))

(provide 'setenv)

;;; setenv.el ends here