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224 lines
8.8 KiB
EmacsLisp
224 lines
8.8 KiB
EmacsLisp
;;; env.el --- functions to manipulate environment variables -*- lexical-binding:t -*-
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;; Copyright (C) 1991, 1994, 2000-2019 Free Software Foundation, Inc.
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;; Maintainer: emacs-devel@gnu.org
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;; Keywords: processes, unix
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;; Package: emacs
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; UNIX processes inherit a list of name-to-string associations from their
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;; parents called their `environment'; these are commonly used to control
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;; program options. This package permits you to set environment variables
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;; to be passed to any sub-process run under Emacs.
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;; Note that the environment string `process-environment' is not
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;; decoded, but the args of `setenv' and `getenv' are normally
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;; multibyte text and get coding conversion.
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;;; Code:
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;; History list for environment variable names.
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(defvar read-envvar-name-history nil)
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(defun read-envvar-name (prompt &optional mustmatch)
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"Read environment variable name, prompting with PROMPT.
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Optional second arg MUSTMATCH, if non-nil, means require existing envvar name.
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If it is also not t, RET does not exit if it does non-null completion."
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(completing-read prompt
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(mapcar (lambda (enventry)
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(let ((str (substring enventry 0
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(string-match "=" enventry))))
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(if (multibyte-string-p str)
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(decode-coding-string
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str locale-coding-system t)
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str)))
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(append process-environment
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;;(frame-environment)
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))
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nil mustmatch nil 'read-envvar-name-history))
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;; History list for VALUE argument to setenv.
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(defvar setenv-history nil)
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(defconst env--substitute-vars-regexp
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"\\$\\(?:\\(?1:[[:alnum:]_]+\\)\\|{\\(?1:[^{}]+\\)}\\|\\$\\)")
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(defun substitute-env-vars (string &optional when-undefined)
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"Substitute environment variables referred to in STRING.
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`$FOO' where FOO is an environment variable name means to substitute
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the value of that variable. The variable name should be terminated
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with a character not a letter, digit or underscore; otherwise, enclose
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the entire variable name in braces. For instance, in `ab$cd-x',
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`$cd' is treated as an environment variable.
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If WHEN-DEFINED is nil, references to undefined environment variables
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are replaced by the empty string; if it is a function, the function is called
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with the variable name as argument and should return the text with which
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to replace it or nil to leave it unchanged.
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If it is non-nil and not a function, references to undefined variables are
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left unchanged.
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Use `$$' to insert a single dollar sign."
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(let ((start 0))
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(while (string-match env--substitute-vars-regexp string start)
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(cond ((match-beginning 1)
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(let* ((var (match-string 1 string))
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(value (getenv var)))
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(if (and (null value)
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(if (functionp when-undefined)
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(null (setq value (funcall when-undefined var)))
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when-undefined))
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(setq start (match-end 0))
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(setq string (replace-match (or value "") t t string)
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start (+ (match-beginning 0) (length value))))))
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(t
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(setq string (replace-match "$" t t string)
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start (+ (match-beginning 0) 1)))))
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string))
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(defun substitute-env-in-file-name (filename)
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(substitute-env-vars filename
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;; How 'bout we lookup other tables than the env?
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;; E.g. we could accept bookmark names as well!
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(if (memq system-type '(windows-nt ms-dos))
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(lambda (var) (getenv (upcase var)))
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t)))
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(defun setenv-internal (env variable value keep-empty)
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"Set VARIABLE to VALUE in ENV, adding empty entries if KEEP-EMPTY.
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Changes ENV by side-effect, and returns its new value."
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(let ((pattern (concat "\\`" (regexp-quote variable) "\\(=\\|\\'\\)"))
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(case-fold-search nil)
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(scan env)
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prev found)
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;; Handle deletions from the beginning of the list specially.
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(if (and (null value)
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(not keep-empty)
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env
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(stringp (car env))
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(string-match-p pattern (car env)))
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(cdr env)
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;; Try to find existing entry for VARIABLE in ENV.
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(while (and scan (stringp (car scan)))
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(when (string-match-p pattern (car scan))
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(if value
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(setcar scan (concat variable "=" value))
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(if keep-empty
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(setcar scan variable)
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(setcdr prev (cdr scan))))
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(setq found t
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scan nil))
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(setq prev scan
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scan (cdr scan)))
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(if (and (not found) (or value keep-empty))
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(cons (if value
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(concat variable "=" value)
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variable)
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env)
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env))))
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;; Fixme: Should the environment be recoded if LC_CTYPE &c is set?
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(defun setenv (variable &optional value substitute-env-vars)
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"Set the value of the environment variable named VARIABLE to VALUE.
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VARIABLE should be a string. VALUE is optional; if not provided or
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nil, the environment variable VARIABLE will be removed.
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Interactively, a prefix argument means to unset the variable, and
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otherwise the current value (if any) of the variable appears at
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the front of the history list when you type in the new value.
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This function always replaces environment variables in the new
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value when called interactively.
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SUBSTITUTE-ENV-VARS, if non-nil, means to substitute environment
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variables in VALUE with `substitute-env-vars', which see.
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This is normally used only for interactive calls.
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The return value is the new value of VARIABLE, or nil if
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it was removed from the environment.
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This function works by modifying `process-environment'.
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As a special case, setting variable `TZ' calls `set-time-zone-rule' as
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a side-effect."
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(interactive
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(if current-prefix-arg
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(list (read-envvar-name "Clear environment variable: " 'exact) nil)
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(let* ((var (read-envvar-name "Set environment variable: " nil))
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(value (getenv var)))
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(when value
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(add-to-history 'setenv-history value))
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;; Here finally we specify the args to give call setenv with.
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(list var
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(read-from-minibuffer (format "Set %s to value: " var)
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nil nil nil 'setenv-history
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value)
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t))))
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(if (and (multibyte-string-p variable) locale-coding-system)
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(let ((codings (find-coding-systems-string (concat variable value))))
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(unless (or (eq 'undecided (car codings))
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(memq (coding-system-base locale-coding-system) codings))
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(error "Can't encode `%s=%s' with `locale-coding-system'"
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variable (or value "")))))
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(and value
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substitute-env-vars
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(setq value (substitute-env-vars value)))
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(if (multibyte-string-p variable)
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(setq variable (encode-coding-string variable locale-coding-system)))
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(if (and value (multibyte-string-p value))
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(setq value (encode-coding-string value locale-coding-system)))
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(if (string-match-p "=" variable)
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(error "Environment variable name `%s' contains `='" variable))
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(if (string-equal "TZ" variable)
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(set-time-zone-rule value))
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(setq process-environment (setenv-internal process-environment
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variable value t))
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value)
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(defun getenv (variable &optional frame)
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"Get the value of environment variable VARIABLE.
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VARIABLE should be a string. Value is nil if VARIABLE is undefined in
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the environment. Otherwise, value is a string.
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If optional parameter FRAME is non-nil, then it should be a
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frame. This function will look up VARIABLE in its `environment'
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parameter.
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Otherwise, this function searches `process-environment' for
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VARIABLE. If it is not found there, then it continues the search
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in the environment list of the selected frame."
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(interactive (list (read-envvar-name "Get environment variable: " t)))
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(let ((value (getenv-internal (if (multibyte-string-p variable)
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(encode-coding-string
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variable locale-coding-system)
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variable)
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(and frame
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(assq 'environment
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(frame-parameters frame))))))
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(if (and enable-multibyte-characters value)
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(setq value (decode-coding-string value locale-coding-system)))
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(when (called-interactively-p 'interactive)
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(message "%s" (if value value "Not set")))
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value))
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(provide 'env)
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;;; env.el ends here
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