-;;; setenv.el --- functions to manipulate environment variables.
+;;; env.el --- functions to manipulate environment variables.
-;;; Copyright Free Software Foundation 1991
+;;; Copyright 1991, 1994 Free Software Foundation, Inc.
+
+;; Maintainer: FSF
+;; Keywords: processes, unix
;;; 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 1, or (at your option)
+;;; 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,
;;; along with GNU Emacs; see the file COPYING. If not, write to
;;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
-(defun setenv (variable value)
+;;; Commentary:
+
+;; UNIX processes inherit a list of name-to-string associations from
+;; their parents called their `environment'; these are commonly used
+;; to control program options. This package permits you to set
+;; environment variables to be passed to any sub-process run under Emacs.
+
+;;; Code:
+
+;; History list for environment variable names.
+(defvar read-envvar-name-history nil)
+
+(defun read-envvar-name (prompt &optional mustmatch)
+ "Read environment variable name, prompting with PROMPT.
+Optional second arg MUSTMATCH, if non-nil, means require existing envvar name.
+If it is also not t, RET does not exit if it does non-null completion."
+ (completing-read prompt
+ (mapcar (function
+ (lambda (enventry)
+ (list (substring enventry 0
+ (string-match "=" enventry)))))
+ process-environment)
+ nil mustmatch nil 'read-envvar-name-history))
+
+;; History list for VALUE argument to setenv.
+(defvar setenv-history nil)
+
+;;;###autoload
+(defun setenv (variable &optional value unset)
"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."
+VARIABLE should be a string. VALUE is optional; if not provided or is
+`nil', the environment variable VARIABLE will be removed.
+
+Interactively, a prefix argument means to unset the variable.
+Interactively, the current value (if any) of the variable
+appears at the front of the history list when you type in the new value.
+
+This function works by modifying `process-environment'."
+ (interactive
+ (if current-prefix-arg
+ (list (read-envvar-name "Clear environment variable: " 'exact) nil t)
+ (let* ((var (read-envvar-name "Set environment variable: " nil))
+ (oldval (getenv var))
+ newval
+ oldhist)
+ ;; Don't put the current value on the history
+ ;; if it is already there.
+ (if (equal oldval (car setenv-history))
+ (setq oldval nil))
+ ;; Now if OLDVAL is non-nil, we should add it to the history.
+ (if oldval
+ (setq setenv-history (cons oldval setenv-history)))
+ (setq oldhist setenv-history)
+ (setq newval (read-from-minibuffer (format "Set %s to value: " var)
+ nil nil nil 'setenv-history))
+ ;; If we added the current value to the history, remove it.
+ ;; Note that read-from-minibuffer may have added the new value.
+ ;; Don't remove that!
+ (if oldval
+ (if (eq oldhist setenv-history)
+ (setq setenv-history (cdr setenv-history))
+ (setcdr setenv-history (cdr (cdr setenv-history)))))
+ ;; Here finally we specify the args to give call setenv with.
+ (list var newval))))
+ (if unset (setq value nil))
(if (string-match "=" variable)
- (error "name of environment variable contains an '=' character")
- (let ((pattern (concat "^" (regexp-quote (concat variable "="))))
- (scan process-environment))
+ (error "Environment variable name `%s' contains `='" variable)
+ (let ((pattern (concat "\\`" (regexp-quote (concat variable "="))))
+ (case-fold-search nil)
+ (scan process-environment)
+ found)
+ (if (string-equal "TZ" variable)
+ (set-time-zone-rule value))
(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))))))))
+ (cond ((string-match pattern (car scan))
+ (setq found t)
+ (if (eq nil value)
+ (setq process-environment (delq (car scan) process-environment))
+ (setcar scan (concat variable "=" value)))
+ (setq scan nil)))
+ (setq scan (cdr scan)))
+ (or found
+ (if value
+ (setq process-environment
+ (cons (concat variable "=" value)
+ process-environment)))))))
-(provide 'setenv)
+(provide 'env)
-;;; setenv.el ends here
+;;; env.el ends here