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112 lines
4.1 KiB
EmacsLisp
112 lines
4.1 KiB
EmacsLisp
;;; env.el --- functions to manipulate environment variables.
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;;; Copyright 1991, 1994 Free Software Foundation, Inc.
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;; Maintainer: FSF
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;; Keywords: processes, unix
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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 2, or (at your option)
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;;; 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; see the file COPYING. If not, write to
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;;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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;;; Commentary:
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;; UNIX processes inherit a list of name-to-string associations from
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;; their parents called their `environment'; these are commonly used
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;; to control program options. This package permits you to set
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;; environment variables to be passed to any sub-process run under Emacs.
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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 (function
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(lambda (enventry)
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(list (substring enventry 0
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(string-match "=" enventry)))))
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process-environment)
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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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;;;###autoload
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(defun setenv (variable &optional value unset)
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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 is
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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.
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Interactively, the current value (if any) of the variable
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appears at the front of the history list when you type in the new value.
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This function works by modifying `process-environment'."
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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 t)
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(let* ((var (read-envvar-name "Set environment variable: " nil))
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(oldval (getenv var))
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newval
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oldhist)
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;; Don't put the current value on the history
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;; if it is already there.
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(if (equal oldval (car setenv-history))
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(setq oldval nil))
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;; Now if OLDVAL is non-nil, we should add it to the history.
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(if oldval
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(setq setenv-history (cons oldval setenv-history)))
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(setq oldhist setenv-history)
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(setq newval (read-from-minibuffer (format "Set %s to value: " var)
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nil nil nil 'setenv-history))
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;; If we added the current value to the history, remove it.
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;; Note that read-from-minibuffer may have added the new value.
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;; Don't remove that!
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(if oldval
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(if (eq oldhist setenv-history)
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(setq setenv-history (cdr setenv-history))
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(setcdr setenv-history (cdr (cdr setenv-history)))))
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;; Here finally we specify the args to give call setenv with.
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(list var newval))))
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(if unset (setq value nil))
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(if (string-match "=" variable)
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(error "Environment variable name `%s' contains `='" variable)
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(let ((pattern (concat "\\`" (regexp-quote (concat variable "="))))
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(case-fold-search nil)
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(scan process-environment)
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found)
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(while scan
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(cond ((string-match pattern (car scan))
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(setq found t)
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(if (eq nil value)
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(setq process-environment (delq (car scan) process-environment))
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(setcar scan (concat variable "=" value)))
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(setq scan nil)))
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(setq scan (cdr scan)))
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(or found
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(if value
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(setq process-environment
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(cons (concat variable "=" value)
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process-environment)))))))
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(provide 'env)
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;;; env.el ends here
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