lisp/env.el

   1 ;;; env.el --- functions to manipulate environment variables.
   2
   3 ;;; Copyright Free Software Foundation 1991
   4
   5 ;; Maintainer: FSF
   6 ;; Keywords: processes, unix
   7
   8 ;;; This file is part of GNU Emacs.
   9
  10 ;;; GNU Emacs is free software; you can redistribute it and/or modify
  11 ;;; it under the terms of the GNU General Public License as published by
  12 ;;; the Free Software Foundation; either version 2, or (at your option)
  13 ;;; any later version.
  14
  15 ;;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;;; GNU General Public License for more details.
  19
  20 ;;; You should have received a copy of the GNU General Public License
  21 ;;; along with GNU Emacs; see the file COPYING.  If not, write to
  22 ;;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  23
  24 ;;; Commentary:
  25
  26 ;; UNIX processes inherit a list of name-to-string associations from
  27 ;; their parents called their `environment'; these are commonly used
  28 ;; to control program options.  This package permits you to set
  29 ;; environment variables to be passed to any sub-process run under Emacs.
  30
  31 ;;; Code:
  32
  33 ;;;###autoload
  34 (defun setenv (variable &optional value)
  35   "Set the value of the environment variable named VARIABLE to VALUE.
  36 VARIABLE should be a string.  VALUE is optional; if not provided or is
  37 `nil', the environment variable VARIABLE will be removed.
  38 This function works by modifying `process-environment'."
  39   (interactive "sSet environment variable: \nsSet %s to value: ")
  40   (if (string-match "=" variable)
  41       (error "Environment variable name `%s' contains `='" variable)
  42     (let ((pattern (concat "\\`" (regexp-quote (concat variable "="))))
  43           (case-fold-search nil)
  44           (scan process-environment))
  45       (while scan
  46         (cond
  47          ((string-match pattern (car scan))
  48           (if (eq nil value)
  49               (setq process-environment (delq (car scan) process-environment))
  50             (setcar scan (concat variable "=" value)))
  51           (setq scan nil))
  52          ((null (setq scan (cdr scan)))
  53           (setq process-environment
  54                 (cons (concat variable "=" value) process-environment))))))))
  55
  56 (provide 'env)
  57
  58 ;;; env.el ends here