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;;; eshell.el --- the Emacs command shell
;; Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004,
;; 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
;; Author: John Wiegley <>
;; Version: 2.5
;; Keywords: processes
;; This file is part of GNU Emacs.
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <>.
;;; Commentary:
;;;_* What does Eshell offer you?
;; Despite the sheer fact that running an Emacs shell can be fun, here
;; are a few of the unique features offered by Eshell:
;; @ Integration with the Emacs Lisp programming environment
;; @ A high degree of configurability
;; @ The ability to have the same shell on every system Emacs has been
;; ported to. Since Eshell imposes no external requirements, and
;; relies upon only the Lisp functions exposed by Emacs, it is quite
;; operating system independent. Several of the common UNIX
;; commands, such as ls, mv, rm, ln, etc., have been implemented in
;; Lisp in order to provide a more consistent work environment.
;; For those who might be using an older version of Eshell, version
;; 2.1 represents an entirely new, module-based architecture. It
;; supports most of the features offered by modern shells. Here is a
;; brief list of some of its more visible features:
;; @ Command argument completion (tcsh, zsh)
;; @ Input history management (bash)
;; @ Intelligent output scrolling
;; @ Pseudo-devices (such as "/dev/clip" for copying to the clipboard)
;; @ Extended globbing (zsh)
;; @ Argument and globbing predication (zsh)
;; @ I/O redirection to buffers, files, symbols, processes, etc.
;; @ Many niceties otherwise seen only in 4DOS
;; @ Alias functions, both Lisp and Eshell-syntax
;; @ Piping, sequenced commands, background jobs, etc...
;;;_* How to begin
;; To start using Eshell, simply type `M-x eshell'.
;;;_* Philosophy
;; A shell is a layer which metaphorically surrounds the kernel, or
;; heart of an operating system. This kernel can be seen as an engine
;; of pure functionality, waiting to serve, while the user programs
;; take advantage of that functionality to accomplish their purpose.
;; The shell's role is to make that functionality accessible to the
;; user in an unformed state. Very roughly, it associates kernel
;; functionality with textual commands, allowing the user to interact
;; with the operating system via linguistic constructs. Process
;; invocation is perhaps the most significant form this takes, using
;; the kernel's `fork' and `exec' functions.
;; Other programs also interact with the functionality of the kernel,
;; but these user applications typically offer a specific range of
;; functionality, and thus are not classed as "shells" proper.
;; (What they lose in quiddity, they gain in rigidity).
;; Emacs is also a user application, but it does make the
;; functionality of the kernel accessible through an interpreted
;; language -- namely, Lisp. For that reason, there is little
;; preventing Emacs from serving the same role as a modern shell. It
;; too can manipulate the kernel in an unpredetermined way to cause
;; system changes. All it's missing is the shell-ish linguistic
;; model.
;; Enter Eshell. Eshell translates "shell-like" syntax into Lisp
;; in order to exercise the kernel in the same manner as typical
;; system shells. There is a fundamental difference here, however,
;; although it may seem subtle at first...
;; Shells like csh and Bourne shell were written several decades ago,
;; in different times, under more restrictive circumstances. This
;; confined perspective shows itself in the paradigm used by nearly
;; all command-line shells since. They are linear in conception, byte
;; stream-based, sequential, and confined to movement within a single
;; host machine.
;; Emacs, on the other hand, is more than just a limited translator
;; that can invoke subprocesses and redirect file handles. It also
;; manages character buffers, windowing frames, network connections,
;; registers, bookmarks, processes, etc. In other words, it's a very
;; multi-dimensional environment, within which eshell emulates a highly
;; linear methodology.
;; Taking a moment, let's look at how this could affect the future of
;; a shell allowed to develop in such a wider field of play:
;; @ There is no reason why directory movement should be linear, and
;; confined to a single file-system. Emacs, through w3 and ange-ftp,
;; has access to the entire Web. Why not allow a user to cd to
;; multiple directories simultaneously, for example? It might make
;; some tasks easier, such as diff'ing files separated by very long
;; pathnames.
;; @ Data sources are available from anywhere Emacs can derive
;; information from: not just from files or the output of other
;; processes.
;; @ Multiple shell invocations all share the same environment -- even
;; the same process list! It would be possible to have "process
;; views", so that one buffer is watching standard output, another
;; standard error, and another the result of standard output grep'd
;; through a regular expression...
;; @ It is not necessary to "leave" the shell, losing all input and
;; output history, environment variables, directory stack, etc.
;; Emacs could save the contents of your eshell environment, and
;; restore all of it (or at least as much as possible) each time you
;; restart. This could occur automatically, without requiring
;; complex initialization scripts.
;; @ Typos occur all of the time; many of them are repeats of common
;; errors, such as 'dri' for `dir'. Since executing non-existent
;; programs is rarely the intention of the user, eshell could prompt
;; for the replacement string, and then record that in a database of
;; known misspellings. (Note: The typo at the beginning of this
;; paragraph wasn't discovered until two months after I wrote the
;; text; it was not intentional).
;; @ Emacs' register and bookmarking facilities can be used for
;; remembering where you've been, and what you've seen -- to varying
;; levels of persistence. They could perhaps even be tied to
;; specific "moments" during eshell execution, which would include
;; the environment at that time, as well as other variables.
;; Although this would require functionality orthogonal to Emacs'
;; own bookmarking facilities, the interface used could be made to
;; operate very similarly.
;; This presents a brief idea of what the fuller dimensionality of an
;; Emacs shell could offer. It's not just the language of a shell
;; that determines how it's used, but also the Weltanschauung
;; underlying its design -- and which is felt behind even the smallest
;; feature. I would hope the freedom provided by using Emacs as a
;; parent environment will invite rich ideas from others. It
;; certainly feels as though all I've done so far is to tie down the
;; horse, so to speak, so that he will run at a man's pace.
;;;_* Influences
;; The author of Eshell has been a long-time user of the following
;; shells, all of which contributed to Eshell's design:
;; @ rc
;; @ bash
;; @ zsh
;; @ sh
;; @ 4nt
;; @ csh
;;;_* Speeding up load time
;; If you find that Eshell loads too slowly, there is something you
;; can do to speed it up.
;; Create a file, named /tmp/elc, containing this filelist:
;; esh-util.elc
;; eshell.elc
;; esh-module.elc
;; esh-var.elc
;; esh-proc.elc
;; esh-arg.elc
;; esh-io.elc
;; esh-ext.elc
;; esh-cmd.elc
;; esh-mode.elc
;; esh-opt.elc
;; em-alias.elc
;; em-banner.elc
;; em-basic.elc
;; em-cmpl.elc
;; em-dirs.elc
;; em-pred.elc
;; em-glob.elc
;; em-hist.elc
;; em-ls.elc
;; em-prompt.elc
;; em-rebind.elc
;; em-script.elc
;; em-smart.elc
;; em-term.elc
;; em-unix.elc
;; em-xtra.elc
;; The order is very important. Remove from the filelist any features
;; you don't use. These all begin with "em-". If you don't use
;; Eshell's key rebinding module, you can remove "em-rebind.elc" from
;; the filelist. The modules you are currently using are listed in
;; `eshell-modules-list'.
;; Now, concatenating all of the above mentioned .elc files, in that
;; order, to another file. Here is how to do this on UNIX:
;; cat `cat /tmp/elc` > tmp.elc ; mv tmp.elc eshell.elc
;; Now your eshell.elc file contains all of the .elc files that make
;; up Eshell, in the right load order. When you next load Eshell, it
;; will only have to read in this one file, which will greatly speed
;; things up.
(require 'cl)
(require 'esh-util))
(require 'esh-util)
(require 'esh-mode)
(defgroup eshell nil
"Eshell is a command shell implemented entirely in Emacs Lisp. It
invokes no external processes beyond those requested by the user. It
is intended to be a functional replacement for command shells such as
bash, zsh, rc, 4dos; since Emacs itself is capable of handling most of
the tasks accomplished by such tools."
:tag "The Emacs shell"
:link '(info-link "(eshell)Top")
:version "21.1"
:group 'applications)
;; This is hack to force make-autoload to put the whole definition
;; into the autoload file (see esh-module.el).
(defalias 'eshell-defgroup 'defgroup)
;;;_* User Options
;; The following user options modify the behavior of Eshell overall.
(defvar eshell-buffer-name)
(defsubst eshell-add-to-window-buffer-names ()
"Add `eshell-buffer-name' to `same-window-buffer-names'."
(add-to-list 'same-window-buffer-names eshell-buffer-name))
(defsubst eshell-remove-from-window-buffer-names ()
"Remove `eshell-buffer-name' from `same-window-buffer-names'."
(setq same-window-buffer-names
(delete eshell-buffer-name same-window-buffer-names)))
(defcustom eshell-load-hook nil
"A hook run once Eshell has been loaded."
:type 'hook
:group 'eshell)
(defcustom eshell-unload-hook
"A hook run when Eshell is unloaded from memory."
:type 'hook
:group 'eshell)
(defcustom eshell-buffer-name "*eshell*"
"The basename used for Eshell buffers."
:set (lambda (symbol value)
;; remove the old value of `eshell-buffer-name', if present
(if (boundp 'eshell-buffer-name)
(set symbol value)
;; add the new value
:type 'string
:group 'eshell)
(eshell-deftest mode same-window-buffer-names
"`eshell-buffer-name' is a member of `same-window-buffer-names'"
(member eshell-buffer-name same-window-buffer-names))
(defcustom eshell-directory-name (convert-standard-filename "~/.eshell/")
"The directory where Eshell control files should be kept."
:type 'directory
:group 'eshell)
(eshell-deftest mode eshell-directory-exists
"`eshell-directory-name' exists and is writable"
(file-writable-p eshell-directory-name))
(eshell-deftest mode eshell-directory-modes
"`eshell-directory-name' has correct access protections"
(or (eshell-under-windows-p)
(= (file-modes eshell-directory-name)
;;;_* Running Eshell
;; There are only three commands used to invoke Eshell. The first two
;; are intended for interactive use, while the third is meant for
;; programmers. They are:
(defun eshell (&optional arg)
"Create an interactive Eshell buffer.
The buffer used for Eshell sessions is determined by the value of
`eshell-buffer-name'. If there is already an Eshell session active in
that buffer, Emacs will simply switch to it. Otherwise, a new session
will begin. A numeric prefix arg (as in `C-u 42 M-x eshell RET')
switches to the session with that number, creating it if necessary. A
nonnumeric prefix arg means to create a new session. Returns the
buffer selected (or created)."
(interactive "P")
(assert eshell-buffer-name)
(let ((buf (cond ((numberp arg)
(get-buffer-create (format "%s<%d>"
(generate-new-buffer eshell-buffer-name))
(get-buffer-create eshell-buffer-name)))))
;; Simply calling `pop-to-buffer' will not mimic the way that
;; shell-mode buffers appear, since they always reuse the same
;; window that that command was invoked from. To achieve this,
;; it's necessary to add `eshell-buffer-name' to the variable
;; `same-window-buffer-names', which is done when Eshell is loaded
(assert (and buf (buffer-live-p buf)))
(pop-to-buffer buf)
(unless (eq major-mode 'eshell-mode)
(defun eshell-return-exits-minibuffer ()
(define-key eshell-mode-map [(control ?g)] 'abort-recursive-edit)
(define-key eshell-mode-map [return] 'exit-minibuffer)
(define-key eshell-mode-map [(control ?m)] 'exit-minibuffer)
(define-key eshell-mode-map [(control ?j)] 'exit-minibuffer)
(define-key eshell-mode-map [(meta return)] 'exit-minibuffer)
(define-key eshell-mode-map [(meta control ?m)] 'exit-minibuffer))
(defvar eshell-non-interactive-p nil
"A variable which is non-nil when Eshell is not running interactively.
Modules should use this variable so that they don't clutter
non-interactive sessions, such as when using `eshell-command'.")
(defun eshell-command (&optional command arg)
"Execute the Eshell command string COMMAND.
With prefix ARG, insert output into the current buffer at point."
(require 'esh-cmd)
(unless arg
(setq arg current-prefix-arg))
(let ((eshell-non-interactive-p t))
(add-hook 'minibuffer-setup-hook 'eshell-mode)
(add-hook 'minibuffer-exit-hook 'eshell-add-command-to-history)
(add-hook 'eshell-mode-hook 'eshell-return-exits-minibuffer)
(unless command
(setq command (read-from-minibuffer "Emacs shell command: "))))
(remove-hook 'eshell-mode-hook 'eshell-return-exits-minibuffer)
(remove-hook 'minibuffer-exit-hook 'eshell-add-command-to-history)
(remove-hook 'minibuffer-setup-hook 'eshell-mode))
(unless command
(error "No command specified!"))
;; redirection into the current buffer is achieved by adding an
;; output redirection to the end of the command, of the form
;; 'COMMAND >>> #<buffer BUFFER>'. This will not interfere with
;; other redirections, since multiple redirections merely cause the
;; output to be copied to multiple target locations
(if arg
(setq command
(concat command
(format " >>> #<buffer %s>"
(buffer-name (current-buffer))))))
(let ((buf (set-buffer (generate-new-buffer " *eshell cmd*")))
(eshell-non-interactive-p t))
(let* ((proc (eshell-eval-command
(list 'eshell-commands
(eshell-parse-command command))))
(bufname (if (and proc (listp proc))
"*EShell Async Command Output*"
(setq intr t)
"*EShell Command Output*")))
(if (buffer-live-p (get-buffer bufname))
(kill-buffer bufname))
(rename-buffer bufname)
;; things get a little coarse here, since the desire is to
;; make the output as attractive as possible, with no
;; extraneous newlines
(when intr
(if (eshell-interactive-process)
(eshell-wait-for-process (eshell-interactive-process)))
(assert (not (eshell-interactive-process)))
(goto-char (point-max))
(while (and (bolp) (not (bobp)))
(delete-backward-char 1)))
(assert (and buf (buffer-live-p buf)))
(unless arg
(let ((len (if (not intr) 2
(count-lines (point-min) (point-max)))))
((= len 0)
(message "(There was no command output)")
(kill-buffer buf))
((= len 1)
(message "%s" (buffer-string))
(kill-buffer buf))
(select-window (display-buffer buf))
(goto-char (point-min))
;; cause the output buffer to take up as little screen
;; real-estate as possible, if temp buffer resizing is
;; enabled
(and intr temp-buffer-resize-mode
(defun eshell-command-result (command &optional status-var)
"Execute the given Eshell COMMAND, and return the result.
The result might be any Lisp object.
If STATUS-VAR is a symbol, it will be set to the exit status of the
command. This is the only way to determine whether the value returned
corresponding to a successful execution."
;; a null command produces a null, successful result
(if (not command)
(if (and status-var (symbolp status-var))
(set status-var 0)))
(let ((eshell-non-interactive-p t))
(let ((result (eshell-do-eval
(list 'eshell-commands
(list 'eshell-command-to-value
(eshell-parse-command command))) t)))
(assert (eq (car result) 'quote))
(if (and status-var (symbolp status-var))
(set status-var eshell-last-command-status))
(cadr result))))))
(eshell-deftest mode simple-command-result
"`eshell-command-result' works with a simple command."
(= (eshell-command-result "+ 1 2") 3))
;;;_* Reporting bugs
;; If you do encounter a bug, on any system, please report
;; it -- in addition to any particular oddities in your configuration
;; -- so that the problem may be corrected for the benefit of others.
(define-obsolete-function-alias 'eshell-report-bug 'report-emacs-bug "23.1")
;;; Code:
(defun eshell-unload-all-modules ()
"Unload all modules that were loaded by Eshell, if possible.
If the user has require'd in any of the modules, or customized a
variable with a :require tag (such as `eshell-prefer-to-shell'), it
will be impossible to unload Eshell completely without restarting
;; if the user set `eshell-prefer-to-shell' to t, but never loaded
;; Eshell, then `eshell-subgroups' will be unbound
(when (fboundp 'eshell-subgroups)
(eshell-for module (eshell-subgroups 'eshell)
;; this really only unloads as many modules as possible,
;; since other `require' references (such as by customizing
;; `eshell-prefer-to-shell' to a non-nil value) might make it
;; impossible to unload Eshell completely
(if (featurep module)
(message "Unloading %s..." (symbol-name module))
(unload-feature module)
(message "Unloading %s...done" (symbol-name module)))))
(message "Unloading eshell...done")))
(run-hooks 'eshell-load-hook)
(provide 'eshell)
;; arch-tag: 9d4d5214-0e4e-4e02-b349-39add640d63f
;;; eshell.el ends here