1;;; env.el --- functions to manipulate environment variables 2 3;; Copyright (C) 1991, 1994, 2000, 2001, 2002, 2003, 2004, 4;; 2005, 2006, 2007 Free Software Foundation, Inc. 5 6;; Maintainer: FSF 7;; Keywords: processes, unix 8 9;; This file is part of GNU Emacs. 10 11;; GNU Emacs is free software; you can redistribute it and/or modify 12;; it under the terms of the GNU General Public License as published by 13;; the Free Software Foundation; either version 2, or (at your option) 14;; any later version. 15 16;; GNU Emacs is distributed in the hope that it will be useful, 17;; but WITHOUT ANY WARRANTY; without even the implied warranty of 18;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 19;; GNU General Public License for more details. 20 21;; You should have received a copy of the GNU General Public License 22;; along with GNU Emacs; see the file COPYING. If not, write to the 23;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 24;; Boston, MA 02110-1301, USA. 25 26;;; Commentary: 27 28;; UNIX processes inherit a list of name-to-string associations from their 29;; parents called their `environment'; these are commonly used to control 30;; program options. This package permits you to set environment variables 31;; to be passed to any sub-process run under Emacs. 32 33;; Note that the environment string `process-environment' is not 34;; decoded, but the args of `setenv' and `getenv' are normally 35;; multibyte text and get coding conversion. 36 37;;; Code: 38 39;; History list for environment variable names. 40(defvar read-envvar-name-history nil) 41 42(defun read-envvar-name (prompt &optional mustmatch) 43 "Read environment variable name, prompting with PROMPT. 44Optional second arg MUSTMATCH, if non-nil, means require existing envvar name. 45If it is also not t, RET does not exit if it does non-null completion." 46 (completing-read prompt 47 (mapcar (lambda (enventry) 48 (list (if enable-multibyte-characters 49 (decode-coding-string 50 (substring enventry 0 51 (string-match "=" enventry)) 52 locale-coding-system t) 53 (substring enventry 0 54 (string-match "=" enventry))))) 55 process-environment) 56 nil mustmatch nil 'read-envvar-name-history)) 57 58;; History list for VALUE argument to setenv. 59(defvar setenv-history nil) 60 61 62(defun substitute-env-vars (string) 63 "Substitute environment variables referred to in STRING. 64`$FOO' where FOO is an environment variable name means to substitute 65the value of that variable. The variable name should be terminated 66with a character not a letter, digit or underscore; otherwise, enclose 67the entire variable name in braces. For instance, in `ab$cd-x', 68`$cd' is treated as an environment variable. 69 70Use `$$' to insert a single dollar sign." 71 (let ((start 0)) 72 (while (string-match 73 (eval-when-compile 74 (rx (or (and "$" (submatch (1+ (regexp "[[:alnum:]_]")))) 75 (and "${" (submatch (minimal-match (0+ anything))) "}") 76 "$$"))) 77 string start) 78 (cond ((match-beginning 1) 79 (let ((value (getenv (match-string 1 string)))) 80 (setq string (replace-match (or value "") t t string) 81 start (+ (match-beginning 0) (length value))))) 82 ((match-beginning 2) 83 (let ((value (getenv (match-string 2 string)))) 84 (setq string (replace-match (or value "") t t string) 85 start (+ (match-beginning 0) (length value))))) 86 (t 87 (setq string (replace-match "$" t t string) 88 start (+ (match-beginning 0) 1))))) 89 string)) 90 91;; Fixme: Should `process-environment' be recoded if LC_CTYPE &c is set? 92 93(defun setenv (variable &optional value substitute-env-vars) 94 "Set the value of the environment variable named VARIABLE to VALUE. 95VARIABLE should be a string. VALUE is optional; if not provided or 96nil, the environment variable VARIABLE will be removed. 97 98Interactively, a prefix argument means to unset the variable. 99Interactively, the current value (if any) of the variable 100appears at the front of the history list when you type in the new value. 101Interactively, always replace environment variables in the new value. 102 103SUBSTITUTE-ENV-VARS, if non-nil, means to substitute environment 104variables in VALUE with `substitute-env-vars', which see. 105This is normally used only for interactive calls. 106 107The return value is the new value of VARIABLE, or nil if 108it was removed from the environment. 109 110This function works by modifying `process-environment'. 111 112As a special case, setting variable `TZ' calls `set-time-zone-rule' as 113a side-effect." 114 (interactive 115 (if current-prefix-arg 116 (list (read-envvar-name "Clear environment variable: " 'exact) nil) 117 (let* ((var (read-envvar-name "Set environment variable: " nil)) 118 (value (getenv var))) 119 (when value 120 (add-to-history 'setenv-history value)) 121 ;; Here finally we specify the args to give call setenv with. 122 (list var 123 (read-from-minibuffer (format "Set %s to value: " var) 124 nil nil nil 'setenv-history 125 value) 126 t)))) 127 (if (and (multibyte-string-p variable) locale-coding-system) 128 (let ((codings (find-coding-systems-string (concat variable value)))) 129 (unless (or (eq 'undecided (car codings)) 130 (memq (coding-system-base locale-coding-system) codings)) 131 (error "Can't encode `%s=%s' with `locale-coding-system'" 132 variable (or value ""))))) 133 (and value 134 substitute-env-vars 135 (setq value (substitute-env-vars value))) 136 (if (multibyte-string-p variable) 137 (setq variable (encode-coding-string variable locale-coding-system))) 138 (if (and value (multibyte-string-p value)) 139 (setq value (encode-coding-string value locale-coding-system))) 140 (if (string-match "=" variable) 141 (error "Environment variable name `%s' contains `='" variable) 142 (let ((pattern (concat "\\`" (regexp-quote (concat variable "=")))) 143 (case-fold-search nil) 144 (scan process-environment) 145 found) 146 (if (string-equal "TZ" variable) 147 (set-time-zone-rule value)) 148 (while scan 149 (cond ((string-match pattern (car scan)) 150 (setq found t) 151 (if (eq nil value) 152 (setq process-environment (delq (car scan) 153 process-environment)) 154 (setcar scan (concat variable "=" value))) 155 (setq scan nil))) 156 (setq scan (cdr scan))) 157 (or found 158 (if value 159 (setq process-environment 160 (cons (concat variable "=" value) 161 process-environment)))))) 162 value) 163 164(defun getenv (variable) 165 "Get the value of environment variable VARIABLE. 166VARIABLE should be a string. Value is nil if VARIABLE is undefined in 167the environment. Otherwise, value is a string. 168 169This function consults the variable `process-environment' 170for its value." 171 (interactive (list (read-envvar-name "Get environment variable: " t))) 172 (let ((value (getenv-internal (if (multibyte-string-p variable) 173 (encode-coding-string 174 variable locale-coding-system) 175 variable)))) 176 (if (and enable-multibyte-characters value) 177 (setq value (decode-coding-string value locale-coding-system))) 178 (when (interactive-p) 179 (message "%s" (if value value "Not set"))) 180 value)) 181 182(provide 'env) 183 184;;; arch-tag: b7d6a8f7-bc81-46db-8e39-8d721d4ed0b8 185;;; env.el ends here 186