lisp/eshell/em-basic.el

   1 ;;; em-basic.el --- basic shell builtin commands
   2
   3 ;; Copyright (C) 1999-2012  Free Software Foundation, Inc.
   4
   5 ;; Author: John Wiegley <johnw@gnu.org>
   6
   7 ;; This file is part of GNU Emacs.
   8
   9 ;; GNU Emacs is free software: you can redistribute it and/or modify
  10 ;; it under the terms of the GNU General Public License as published by
  11 ;; the Free Software Foundation, either version 3 of the License, or
  12 ;; (at your option) any later version.
  13
  14 ;; GNU Emacs is distributed in the hope that it will be useful,
  15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 ;; GNU General Public License for more details.
  18
  19 ;; You should have received a copy of the GNU General Public License
  20 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  21
  22 ;;; Commentary:
  23
  24 ;; There are very few basic Eshell commands -- so-called builtins.
  25 ;; They are: echo, umask, and version.
  26 ;;
  27 ;;;_* `echo'
  28 ;;
  29 ;; The `echo' command repeats its arguments to the screen.  It is
  30 ;; optional whether this is done in a Lisp-friendly fashion (so that
  31 ;; the value of echo is useful to a Lisp command using the result of
  32 ;; echo as an argument), or whether it should try to act like a normal
  33 ;; shell echo, and always result in a flat string being returned.
  34
  35 ;; An example of the difference is the following:
  36 ;;
  37 ;;   echo Hello world
  38 ;;
  39 ;; If `eshell-plain-echo-behavior' is non-nil, this will yield the
  40 ;; string "Hello world".  If Lisp behavior is enabled, however, it
  41 ;; will yield a list whose two elements are the strings "Hello" and
  42 ;; "world".  The way to write an equivalent expression for both would
  43 ;; be:
  44 ;;
  45 ;;   echo "Hello world"
  46 ;;
  47 ;; This always returns a single string.
  48 ;;
  49 ;;;_* `umask'
  50 ;;
  51 ;; The umask command changes the default file permissions for newly
  52 ;; created files.  It uses the same syntax as bash.
  53 ;;
  54 ;;;_* `version'
  55 ;;
  56 ;; This command reports the version number for Eshell and all its
  57 ;; dependent module, including the date when those modules were last
  58 ;; modified.
  59
  60 ;;; Code:
  61
  62 (eval-when-compile
  63   (require 'esh-util))
  64
  65 (require 'eshell)
  66 (require 'esh-opt)
  67
  68 ;;;###autoload
  69 (progn
  70 (defgroup eshell-basic nil
  71   "The \"basic\" code provides a set of convenience functions which
  72 are traditionally considered shell builtins.  Since all of the
  73 functionality provided by them is accessible through Lisp, they are
  74 not really builtins at all, but offer a command-oriented way to do the
  75 same thing."
  76   :tag "Basic shell commands"
  77   :group 'eshell-module))
  78
  79 (defcustom eshell-plain-echo-behavior nil
  80   "If non-nil, `echo' tries to behave like an ordinary shell echo.
  81 This comes at some detriment to Lisp functionality.  However, the Lisp
  82 equivalent of `echo' can always be achieved by using `identity'."
  83   :type 'boolean
  84   :group 'eshell-basic)
  85
  86 ;;; Functions:
  87
  88 (defun eshell-echo (args &optional output-newline)
  89   "Implementation code for a Lisp version of `echo'.
  90 It returns a formatted value that should be passed to `eshell-print'
  91 or `eshell-printn' for display."
  92   (if eshell-plain-echo-behavior
  93       (concat (apply 'eshell-flatten-and-stringify args) "\n")
  94     (let ((value
  95            (cond
  96             ((= (length args) 0) "")
  97             ((= (length args) 1)
  98              (car args))
  99             (t
 100              (mapcar
 101               (function
 102                (lambda (arg)
 103                  (if (stringp arg)
 104                      (set-text-properties 0 (length arg) nil arg))
 105                  arg))
 106               args)))))
 107       (if output-newline
 108           (cond
 109            ((stringp value)
 110             (concat value "\n"))
 111            ((listp value)
 112             (append value (list "\n")))
 113            (t
 114             (concat (eshell-stringify value) "\n")))
 115         value))))
 116
 117 (defun eshell/echo (&rest args)
 118   "Implementation of `echo'.  See `eshell-plain-echo-behavior'."
 119   (eshell-eval-using-options
 120    "echo" args
 121    '((?n nil nil output-newline "terminate with a newline")
 122      (?h "help" nil nil "output this help screen")
 123      :preserve-args
 124      :usage "[-n] [object]")
 125    (eshell-echo args output-newline)))
 126
 127 (defun eshell/printnl (&rest args)
 128   "Print out each of the arguments, separated by newlines."
 129   (let ((elems (eshell-flatten-list args)))
 130     (while elems
 131       (eshell-printn (eshell-echo (list (car elems))))
 132       (setq elems (cdr elems)))))
 133
 134 (defun eshell/listify (&rest args)
 135   "Return the argument(s) as a single list."
 136   (if (> (length args) 1)
 137       args
 138     (if (listp (car args))
 139         (car args)
 140       (list (car args)))))
 141
 142 (defun eshell/umask (&rest args)
 143   "Shell-like implementation of `umask'."
 144   (eshell-eval-using-options
 145    "umask" args
 146    '((?S "symbolic" nil symbolic-p "display umask symbolically")
 147      (?h "help" nil nil  "display this usage message")
 148      :usage "[-S] [mode]")
 149    (if (or (not args) symbolic-p)
 150        (let ((modstr
 151               (concat "000"
 152                       (format "%o"
 153                               (logand (lognot (default-file-modes))
 154                                       511)))))
 155          (setq modstr (substring modstr (- (length modstr) 3)))
 156          (when symbolic-p
 157            (let ((mode (default-file-modes)))
 158              (setq modstr
 159                    (format
 160                     "u=%s,g=%s,o=%s"
 161                     (concat (and (= (logand mode 64) 64) "r")
 162                             (and (= (logand mode 128) 128) "w")
 163                             (and (= (logand mode 256) 256) "x"))
 164                     (concat (and (= (logand mode 8) 8) "r")
 165                             (and (= (logand mode 16) 16) "w")
 166                             (and (= (logand mode 32) 32) "x"))
 167                     (concat (and (= (logand mode 1) 1) "r")
 168                             (and (= (logand mode 2) 2) "w")
 169                             (and (= (logand mode 4) 4) "x"))))))
 170          (eshell-printn modstr))
 171      (setcar args (eshell-convert (car args)))
 172      (if (numberp (car args))
 173          (set-default-file-modes
 174           (- 511 (car (read-from-string
 175                        (concat "?\\" (number-to-string (car args)))))))
 176        (error "setting umask symbolically is not yet implemented"))
 177      (eshell-print
 178       "Warning: umask changed for all new files created by Emacs.\n"))
 179    nil))
 180
 181 (provide 'em-basic)
 182
 183 ;; Local Variables:
 184 ;; generated-autoload-file: "esh-groups.el"
 185 ;; End:
 186
 187 ;;; em-basic.el ends here