;;; Code:
;;;###autoload
-(defun setenv (variable &optional value)
+(defun setenv (variable &optional value unset)
"Set the value of the environment variable named VARIABLE to VALUE.
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.
This function works by modifying `process-environment'."
- (interactive "sSet environment variable: \nsSet %s to value: ")
+ (interactive
+ (if current-prefix-arg
+ (list (read-string "Clear environment variable: ") nil t)
+ (let ((var (read-string "Set environment variable: ")))
+ (list var (read-string (format "Set %s to value: " var))))))
+ (if unset (setq value nil))
(if (string-match "=" variable)
(error "Environment variable name `%s' contains `='" variable)
(let ((pattern (concat "\\`" (regexp-quote (concat variable "="))))
(case-fold-search nil)
- (scan process-environment))
- (if scan
- (while scan
- (cond
- ((string-match pattern (car scan))
- (if (eq nil value)
- (setq process-environment (delq (car scan) process-environment))
- (setcar scan (concat variable "=" value)))
- (setq scan nil))
- ((null (setq scan (cdr scan)))
+ (scan process-environment)
+ found)
+ (while scan
+ (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)))))
- (setq process-environment
- (cons (concat variable "=" value) process-environment))))))
+ (cons (concat variable "=" value)
+ process-environment)))))))
(provide 'env)