Eshell
******

Eshell is a shell-like command interpreter implemented in Emacs Lisp. It invokes no external processes except for those requested by the user.  It is intended to be an alternative to the IELM (see Emacs Lisp Interaction (The Emacs Editor)) REPL for Emacs and with an interface similar to command shells such as bash, zsh, rc, or 4dos.

This manual is for Eshell, the Emacs shell.

Copyright © 1999--2015 Free Software Foundation, Inc.

     Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover Texts being ``A GNU Manual'', and with the Back-Cover Texts as in (a) below.  A copy of the license is included in the section entitled ``GNU Free Documentation License''.

     (a) The FSF's Back-Cover Text is: ``You have the freedom to copy and modify this GNU manual.''

Introduction
************

What is Eshell?
===============

Eshell is a command shell written in Emacs Lisp.  Everything it does, it uses Emacs's facilities to do.  This means that Eshell is as portable as Emacs itself.  It also means that cooperation with Lisp code is natural and seamless.

What is a command shell?  To properly understand the role of a shell, it's necessary to visualize what a computer does for you.  Basically, a computer is a tool; in order to use that tool, you must tell it what to do---or give it ``commands.''  These commands take many forms, such as clicking with a mouse on certain parts of the screen.  But that is only one form of command input.

By far the most versatile way to express what you want the computer to do is by using an abbreviated language called script.  In script, instead of telling the computer, ``list my files, please'', one writes a standard abbreviated command word---ls.  Typing ls in a command shell is a script way of telling the computer to list your files. (This is comparable to viewing the contents of a folder using a graphical display.)

The real flexibility of this approach is apparent only when you realize that there are many, many different ways to list files.  Perhaps you want them sorted by name, sorted by date, in reverse order, or grouped by type.  Most graphical browsers have simple ways to express this.  But what about showing only a few files, or only files that meet a certain criteria?  In very complex and specific situations, the request becomes too difficult to express using a mouse or pointing device.  It is just these kinds of requests that are easily solved using a command shell.

For example, what if you want to list every Word file on your hard drive, larger than 100 kilobytes in size, and which hasn't been looked at in over six months?  That is a good candidate list for deletion, when you go to clean up your hard drive.  But have you ever tried asking your computer for such a list?  There is no way to do it!  At least, not without using a command shell.

The role of a command shell is to give you more control over what your computer does for you.  Not everyone needs this amount of control, and it does come at a cost: Learning the necessary script commands to express what you want done.  A complicated query, such as the example above, takes time to learn.  But if you find yourself using your computer frequently enough, it is more than worthwhile in the long run. Any tool you use often deserves the time spent learning to master it. (For the understandably curious, here is what that command looks like: But don't let it fool you; once you know what's going on, it's easier than it looks: ls -lt **/*.doc(Lk+50aM+5).)

What Eshell is not
==================

Eshell is not a replacement for system shells such as bash or zsh.  Use Eshell when you want to move text between Emacs and external processes; if you only want to pipe output from one external process to another (and then another, and so on), use a system shell, because Emacs's IO system is buffer oriented, not stream oriented, and is very inefficient at such tasks.  If you want to write shell scripts in Eshell, don't; either write an elisp library or use a system shell.

Some things Eshell just doesn't do well.  It fills the niche between IELM and your system shell, where the peculiar use-cases lie, and it is less than ideal outside that niche.

Contributors to Eshell
======================

Contributions to Eshell are welcome.  I have limited time to work on this project, but I will gladly add any code you contribute to me to this package.

The following persons have made contributions to Eshell.

  * Eli Zaretskii made it possible for Eshell to run without requiring asynchronous subprocess support.  This is important for MS-DOS, which does not have such support.

  * Miles Bader contributed many fixes during the port to Emacs 21.

  * Stefan Monnier fixed the things which bothered him, which of course made things better for all.

  * Gerd Moellmann also helped to contribute bug fixes during the initial integration with Emacs 21.

  * Alex Schroeder contributed code for interactively querying the user before overwriting files.

  * Sudish Joseph helped with some XEmacs compatibility issues.

Apart from these, a lot of people have sent suggestions, ideas, requests, bug reports and encouragement.  Thanks a lot!  Without you there would be no new releases of Eshell.

Commands
********

In a command shell, everything is done by invoking commands.  This chapter covers command invocations in Eshell, including the command history and invoking commands in a script file.

Invocation
==========

Unlike regular system shells, Eshell never invokes kernel functions directly, such as exec(3).  Instead, it uses the Lisp functions available in the Emacs Lisp library.  It does this by transforming the input line into a callable Lisp form. (To see the Lisp form that will be invoked, type: eshell-parse-command "echo hello")

The command can be either an Elisp function or an external command. Eshell looks first for an alias with the same name as the command, then a built-in command or a function with the same name; if there is no match, it then tries to execute it as an external command.

The semicolon (;) can be used to separate multiple command invocations on a single line.  A command invocation followed by an ampersand (&) will be run in the background.  Eshell has no job control, so you can not suspend or background the current process, or bring a background process into the foreground.  That said, background processes invoked from Eshell can be controlled the same way as any other background process in Emacs.

Arguments
=========

Command arguments are passed to the functions as either strings or numbers, depending on what the parser thinks they look like.  If you need to use a function that takes some other data type, you will need to call it in an Elisp expression (which can also be used with expansions).  As with other shells, you can escape special characters and spaces with the backslash (\) and apostrophes ('') and double quotes ("").

Built-in commands
=================

Several commands are built-in in Eshell.  In order to call the external variant of a built-in command foo, you could call *foo.  Usually, this should not be necessary.  You can check what will be applied by the which command:

     ~ $ which ls
     eshell/ls is a compiled Lisp function in `em-ls.el'
     ~ $ which *ls
     /bin/ls

If you want to discard a given built-in command, you could declare an alias, Aliases.  Example:

     ~ $ which sudo
     eshell/sudo is a compiled Lisp function in `em-unix.el'
     ~ $ alias sudo '*sudo $*'
     ~ $ which sudo
     sudo is an alias, defined as "*sudo $*"

If you would prefer to use the built-in commands instead of the external commands, set eshell-prefer-lisp-functions to t.

Some of the built-in commands have different behavior from their external counterparts, and some have no external counterpart.  Most of these will print a usage message when given the --help option.

addpath
     Adds a given path or set of paths to the PATH environment variable, or, with no arguments, prints the current paths in this variable.

alias
     Define an alias (see Aliases).  This does not add it to the aliases file.

clear
     Scrolls the contents of the eshell window out of sight, leaving a blank window. If provided with an optional non-nil argument, the scrollback contents are cleared instead.

date
     Similar to, but slightly different from, the GNU Coreutils date command.

define
     Define a varalias. See Variable Aliases (The Emacs Lisp Reference Manual).

diff
     Use Emacs's internal diff (not to be confused with ediff).  See Comparing Files (The GNU Emacs Manual).

grep
agrep
egrep
fgrep
glimpse
     The grep commands are compatible with GNU grep, but use Emacs's internal grep instead.

info
     Same as the external info command, but uses Emacs's internal Info reader.

jobs
     List subprocesses of the Emacs process, if any, using the function list-processes.

kill
     Kill processes.  Takes a PID or a process object and an optional signal specifier.

listify
     Eshell version of list.  Allows you to create a list using Eshell syntax, rather than Elisp syntax.  For example, listify foo bar and ("foo" "bar") both evaluate to ("foo" "bar").

locate
     Alias to Emacs's locate function, which simply runs the external locate command and parses the results. See Dired and Find (The GNU Emacs Manual).

make
     Run make through compile. See Compilation (The GNU Emacs Manual).

occur
     Alias to Emacs's occur. See Other Repeating Search (The GNU Emacs Manual).

printnl
     Print the arguments separated by newlines.

cd
     This command changes the current working directory.  Usually, it is invoked as cd foo where foo is the new working directory. But cd knows about a few special arguments:

     When it receives no argument at all, it changes to the home directory.

     Giving the command cd - changes back to the previous working directory (this is the same as cd $-).

     The command cd = shows the directory stack.  Each line is numbered.

     With cd =foo, Eshell searches the directory stack for a directory matching the regular expression foo and changes to that directory.

     With cd -42, you can access the directory stack by number.

su
sudo
     Uses TRAMP's su or sudo method see Inline methods (tramp) to run a command via su or sudo.  These commands are in the eshell-tramp module, which is disabled by default.

Built-in variables
------------------

Eshell knows a few built-in variables:

$+
     This variable always contains the current working directory.

$-
     This variable always contains the previous working directory (the current working directory from before the last cd command).

$_
     It refers to the last argument of the last command.

$$
     This is the result of the last command.  In case of an external command, it is t or nil.

$?
     This variable contains the exit code of the last command (0 or 1 for Lisp functions, based on successful completion).

Variables
=========

Since Eshell is just an Emacs REPL (Read-Eval-Print Loop), it does not have its own scope, and simply stores variables the same you would in an Elisp program.  Eshell provides a command version of setq for convenience.

Aliases
=======

Aliases are commands that expand to a longer input line.  For example, ll is a common alias for ls -l, and would be defined with the command invocation alias ll ls -l; with this defined, running ll foo in Eshell will actually run ls -l foo. Aliases defined (or deleted) by the alias command are automatically written to the file named by eshell-aliases-file, which you can also edit directly (although you will have to manually reload it).

History
=======

The history command shows all commands kept in the history ring as numbered list.  If the history ring contains eshell-history-size commands, those numbers change after every command invocation, therefore the history command shall be applied before using the expansion mechanism with history numbers.

The n-th entry of the history ring can be applied with the !n command.  If n is negative, the entry is counted from the end of the history ring.

!foo expands to the last command beginning with foo, and !?foo to the last command containing foo.  The n-th argument of the last command beginning with foo is accessible by !foo:n.

The history ring is loaded from a file at the start of every session, and written back to the file at the end of every session.  The file path is specified in eshell-history-file-name.  Unlike other shells, such as Bash, Eshell can not be configured to keep a history ring of a different size than that of the history file.

Since the default buffer navigation and searching key-bindings are still present in the Eshell buffer, the commands for history navigation and searching are bound to different keys:

M-r
M-s
     History I-search.

M-p
M-n
     Previous and next history line.  If there is anything on the input line when you run these commands, they will instead jump to the precious or next line that begins with that string.

Completion
==========

Eshell uses the pcomplete package for programmable completion, similar to that of other command shells.  Argument completion differs depending on the preceding command: for example, possible completions for rmdir are only directories, while rm completions can be directories and files.  Eshell provides predefined completions for the built-in functions and some common external commands, and you can define your own for any command.

Eshell completion also works for lisp forms and glob patterns. If the point is on a lisp form, then TAB will behave similarly to completion in elisp-mode and lisp-interaction-mode.  For glob patterns, If there are few enough possible completions of the patterns, they will be cycled when TAB is pressed, otherwise it will be removed from the input line and the possible completions will be listed.

If you want to see the entire list of possible completions when it's below the cycling threshold, press M-?.

pcomplete
---------

Pcomplete, short for programmable completion, is the completion library originally written for Eshell, but usable for command completion (Command completion as opposed to code completion, which is a beyond the scope of pcomplete.)  in other modes.

Completions are defined as functions (with defun) named pcomplete/COMMAND, where COMMAND is the name of the command for which this function provides completions; you can also name the function pcomplete/MAJOR-MODE/COMMAND to define completions for a specific major mode.

for loop
========

Because Eshell commands can not (easily) be combined with lisp forms, Eshell provides a command-oriented for-loop for convenience. The syntax is as follows:

     for VAR in TOKENS { command invocation(s) }

where TOKENS is a space-separated sequence of values of VAR for each iteration.  This can even be the output of a command if TOKENS is replaced with { command invocation }.

Scripts
=======

You can run Eshell scripts much like scripts for other shells; the main difference is that since Eshell is not a system command, you have to run it from within Emacs.  An Eshell script is simply a file containing a sequence of commands, as with almost any other shell script.  Scripts are invoked from Eshell with source, or from anywhere in Emacs with eshell-source-file.

If you wish to load a script into your current environment, rather than in a subshell, use the . command.

Expansion
*********

Expansion in a command shell is somewhat like macro expansion in macro parsers (such as cpp and m4), but in a command shell, they are less often used for constants, and usually for using variables and string manipulation. (Eshell has no string-manipulation expansions because the Elisp library already provides many functions for this.)  For example, $var on a line expands to the value of the variable var when the line is executed.  Expansions are usually passed as arguments, but may also be used as commands. (E.g., entering just $var at the prompt is equivalent to entering the value of var at the prompt.)

Dollars Expansion
=================

Eshell has different $ expansion syntax from other shells.  There are some similarities, but don't let these lull you into a false sense of familiarity.

$var
     Expands to the value bound to var.  This is the main way to use variables in command invocations.

$#var
     Expands to the length of the value bound to var.  Raises an error if the value is not a sequence (see Sequences (The Emacs Lisp Reference Manual)).

$(lisp)
     Expands to the result of evaluating the S-expression (lisp).  On its own, this is identical to just (lisp), but with the $, it can be used in a string, such as /some/path/$(lisp).txt.

${command}
     Returns the output of command, which can be any valid Eshell command invocation, and may even contain expansions.

$var[i]
     Expands to the ith element of the value bound to var.  If the value is a string, it will be split at whitespace to make it a list. Again, raises an error if the value is not a sequence.

$var[: i]
     As above, but now splitting occurs at the colon character.

$var[: i j]
     As above, but instead of returning just a string, it now returns a list of two strings.  If the result is being interpolated into a larger string, this list will be flattened into one big string, with each element separated by a space.

$var["\\\\" i]
     Separate on backslash characters.  Actually, the first argument -- if it doesn't have the form of a number, or a plain variable name -- can be any regular expression.  So to split on numbers, use $var["[0-9]+" 10 20].

$var[hello]
     Calls assoc on var with "hello", expecting it to be an alist (see Association Lists (The Emacs Lisp Reference Manual)).

$#var[hello]
     Returns the length of the cdr of the element of var who car is equal to "hello".

Globbing
========

Eshell's globbing syntax is very similar to that of Zsh.  Users coming from Bash can still use Bash-style globbing, as there are no incompatibilities.  Most globbing is pattern-based expansion, but there is also predicate-based expansion.  See Filename Generation (The Z Shell Manual) for full syntax.  To customize the syntax and behavior of globbing in Eshell see the Customize (see Easy Customization (The GNU Emacs Manual).) groups ``eshell-glob'' and ``eshell-pred''.

Input/Output
************

Since Eshell does not communicate with a terminal like most command shells, IO is a little different.

Visual Commands
===============

If you try to run programs from within Eshell that are not line-oriented, such as programs that use ncurses, you will just get garbage output, since the Eshell buffer is not a terminal emulator. Eshell solves this problem by running such programs in Emacs's terminal emulator.

Programs that need a terminal to display output properly are referred to in this manual as ``visual commands,'' because they are not simply line-oriented.  You must tell Eshell which commands are visual, by adding them to eshell-visual-commands; for commands that are visual for only certain sub-commands -- e.g., git log but not git status -- use eshell-visual-subcommands; and for commands that are visual only when passed certain options, use eshell-visual-options.

Caution: Some tools such as Git use the pager less by default to paginate their output but call it with its -F option.  This option causes less to echo the output instead of paginating it if the output is less than one page long.  This causes undesirable behavior if, e.g., git diff, is defined as a visual subcommand. It'll work if the output is big enough and fail if it is less than one page long.  If that occurs to you, search for configuration options for calling less without the -F option.  For Git, you can do that using git config --global core.pager 'less -+F'.

Redirection
===========

Redirection is mostly the same in Eshell as it is in other command shells.  The output redirection operators > and >> as well as pipes are supported, but there is not yet any support for input redirection.  Output can also be redirected to buffers, using the >>> redirection operator, and Elisp functions, using virtual devices.

The buffer redirection operator, >>>, expects a buffer object on the right-hand side, into which it inserts the output of the left-hand side.  e.g., echo hello >>> #<buffer *scratch*> inserts the string "hello" into the *scratch* buffer.

eshell-virtual-targets is a list of mappings of virtual device names to functions.  Eshell comes with two virtual devices: /dev/kill, which sends the text to the kill ring, and /dev/clip, which sends text to the clipboard.

You can, of course, define your own virtual targets.  They are defined by adding a list of the form ("/dev/name" FUNCTION MODE) to eshell-virtual-targets.  The first element is the device name; FUNCTION may be either a lambda or a function name.  If MODE is nil, then the function is the output function; if it is non-nil, then the function is passed the redirection mode as a symbol--overwrite for >, append for >>, or insert for >>>--and the function is expected to return the output function.

The output function is called once on each line of output until nil is passed, indicating end of output.

Extension modules
*****************

Eshell provides a facility for defining extension modules so that they can be disabled and enabled without having to unload and reload them, and to provide a common parent Customize group for the modules. (ERC provides a similar module facility.)  An Eshell module is defined the same as any other library but one requirement: the module must define a Customize (see Customization (The Emacs Lisp Reference Manual).) group using eshell-defgroup (in place of defgroup) with eshell-module as the parent group. (If the module has no user-customizable options, then there is no need to define it as an Eshell module.)  You also need to load the following as shown:

     (eval-when-compile
       (require 'cl-lib)
       (require 'esh-mode)
       (require 'eshell))

     (require 'esh-util)

Writing a module
================

Module testing
==============

Directory handling
==================

Key rebinding
=============

Smart scrolling
===============

Terminal emulation
==================

Bugs and ideas
**************

If you find a bug or misfeature, don't hesitate to report it, by using M-x report-emacs-bug.  The same applies to feature requests. It is best to discuss one thing at a time.  If you find several unrelated bugs, please report them separately.

Below is a list of some known problems with Eshell version 2.4.2, which is the version included with Emacs 22.

Documentation incomplete

Differentiate between aliases and functions

     Allow for a Bash-compatible syntax, such as:

          alias arg=blah
          function arg () { blah $* }

for i in 1 2 3 { grep -q a b && *echo has it } | wc -l outputs result after prompt

     In fact, piping to a process from a looping construct doesn't work in general.  If I change the call to eshell-copy-handles in eshell-rewrite-for-command to use eshell-protect, it seems to work, but the output occurs after the prompt is displayed.  The whole structured command thing is too complicated at present.

Error with bc in eshell-test

     On some XEmacs system, the subprocess interaction test fails inexplicably, although bc works fine at the command prompt.

Eshell does not delete *Help* buffers in XEmacs 21.1.8+

     In XEmacs 21.1.8, the *Help* buffer has been renamed such that multiple instances of the *Help* buffer can exist.

Pcomplete sometimes gets stuck

     You press TAB, but no completions appear, even though the directory has matching files.  This behavior is rare.

grep python $<rpm -qa> doesn't work, but using *grep does

     This happens because the grep Lisp function returns immediately, and then the asynchronous grep process expects to examine the temporary file, which has since been deleted.

Problem with C-r repeating text

     If the text before point reads "./run", and you type C-r r u n, it will repeat the line for every character typed.

Backspace doesn't scroll back after continuing (in smart mode)

     Hitting space during a process invocation, such as make, will cause it to track the bottom of the output; but backspace no longer scrolls back.

It's not possible to fully unload-feature Eshell

Menu support was removed, but never put back

Using C-p and C-n with rebind gets into a locked state

     This happened a few times in Emacs 21, but has been irreproducible since.

If an interactive process is currently running, M-! doesn't work

Use a timer instead of sleep-for when killing child processes

Piping to a Lisp function is not supported

     Make it so that the Lisp command on the right of the pipe is repeatedly called with the input strings as arguments.  This will require changing eshell-do-pipeline to handle non-process targets.

Input redirection is not supported

     See the above entry.

Problem running less without arguments on Windows

     The result in the Eshell buffer is:

          Spawning child process: invalid argument

     Also a new less buffer was created with nothing in it... (presumably this holds the output of less).

     If less.exe is invoked from the Eshell command line, the expected output is written to the buffer.

     Note that this happens on NT-Emacs 20.6.1 on Windows 2000. The term.el package and the supplied shell both use the cmdproxy program for running shells.

Implement -r, -n and -s switches for cp

Make M-5 M-x eshell switch to ``*eshell<5>*'', creating if need be

mv DIR FILE.tar does not remove directories

     This is because the tar option --remove-files doesn't do so.  Should it be Eshell's job?

Bind standard-output and standard-error

     This would be so that if a Lisp function calls print, everything will happen as it should (albeit slowly).

When an extension module fails to load, cd / gives a Lisp error

If a globbing pattern returns one match, should it be a list?

Make sure syntax table is correct in Eshell mode

     So that M-DEL acts in a predictable manner, etc.

Allow all Eshell buffers to share the same history and list-dir

There is a problem with script commands that output to /dev/null

     If a script file, somewhere in the middle, uses > /dev/null, output from all subsequent commands is swallowed.

Split up parsing of text after $ in esh-var.el

     Make it similar to the way that esh-arg.el is structured. Then add parsing of $[?\n].

After pressing M-RET, redisplay before running the next command

Argument predicates and modifiers should work anywhere in a path

          /usr/local/src/editors/vim $ vi **/CVS(/)/Root(.)
          Invalid regexp: "Unmatched ( or \\("

     With zsh, the glob above expands to all files named Root in directories named CVS.

Typing echo ${locate locate}/bin<TAB> results in a Lisp error

     Perhaps it should interpolate all permutations, and make that the globbing result, since otherwise hitting return here will result in ``(list of filenames)/bin'', which is never valuable.  Thus, one could cat only C backup files by using ls ${identity *.c}~. In that case, having an alias command name glob for identity would be useful.

Once symbolic mode is supported for umask, implement chmod in Lisp

Create eshell-expand-file-name

     This would use a data table to transform things such as ~+, ..., etc.

Abstract em-smart.el into smart-scroll.el

     It only really needs: to be hooked onto the output filter and the pre-command hook, and to have the input-end and input-start markers. And to know whether the last output group was ``successful.''

Allow for fully persisting the state of Eshell

     This would include: variables, history, buffer, input, dir stack, etc.

Implement D as an argument predicate

     It means that files beginning with a dot should be included in the glob match.

A comma in a predicate list should mean OR

     At the moment, this is not supported.

Error if a glob doesn't expand due to a predicate

     An error should be generated only if eshell-error-if-no-glob is non-nil.

(+ RET SPC TAB does not cause indent-according-to-mode to occur

Create eshell-auto-accumulate-list

     This is a list of commands for which, if the user presses RET, the text is staged as the next Eshell command, rather than being sent to the current interactive process.

Display file and line number if an error occurs in a script

wait doesn't work with process ids at the moment

Enable the direct-to-process input code in em-term.el

Problem with repeating echo ${find /tmp}

     With smart display active, if RET is held down, after a while it can't keep up anymore and starts outputting blank lines.  It only happens if an asynchronous process is involved...

     I think the problem is that eshell-send-input is resetting the input target location, so that if the asynchronous process is not done by the time the next RET is received, the input processor thinks that the input is meant for the process; which, when smart display is enabled, will be the text of the last command line!  That is a bug in itself.

     In holding down RET while an asynchronous process is running, there will be a point in between termination of the process, and the running of eshell-post-command-hook, which would cause eshell-send-input to call eshell-copy-old-input, and then process that text as a command to be run after the process.  Perhaps there should be a way of killing pending input between the death of the process, and the post-command-hook.

Allow for a more aggressive smart display mode

     Perhaps toggled by a command, that makes each output block a smart display block.

Create more meta variables

     $!
          The reason for the failure of the last disk command, or the text of the last Lisp error.

     $=
          A special associate array, which can take references of the form $=[REGEXP].  It indexes into the directory ring.

Eshell scripts can't execute in the background

Support zsh's ``Parameter Expansion'' syntax, i.e., ${NAME:-VAL}

Write an info alias that can take arguments

     So that the user can enter info chmod, for example.

Create a mode eshell-browse

     It would treat the Eshell buffer as a outline.  Collapsing the outline hides all of the output text.  Collapsing again would show only the first command run in each directory

Allow other revisions of a file to be referenced using file{rev}

     This would be expanded by eshell-expand-file-name (see above).

Print ``You have new mail'' when the ``Mail'' icon is turned on

Implement M-| for Eshell

Implement input redirection

     If it's a Lisp function, input redirection implies xargs (in a way...).  If input redirection is added, also update the file-name-quote-list, and the delimiter list.

Allow #<WORD ARG> as a generic syntax

     With the handling of word specified by an eshell-special-alist.

In eshell-eval-using-options, allow a :complete tag

     It would be used to provide completion rules for that command.  Then the macro will automagically define the completion function.

For eshell-command-on-region, apply redirections to the result

     So that + > 'blah would cause the result of the + (using input from the current region) to be inserting into the symbol blah.

     If an external command is being invoked, the input is sent as standard input, as if a cat <region> | had been invoked.

     If a Lisp command, or an alias, is invoked, then if the line has no newline characters, it is divided by whitespace and passed as arguments to the Lisp function.  Otherwise, it is divided at the newline characters.  Thus, invoking + on a series of numbers will add them; min would display the smallest figure, etc.

Write eshell-script-mode as a minor mode

     It would provide syntax, abbrev, highlighting and indenting support like emacs-lisp-mode and shell-mode.

In the history mechanism, finish the Bash-style support

     This means !n, !#, !:%, and !:1- as separate from !:1*.

Support the -n command line option for history

Implement fc in Lisp

Specifying a frame as a redirection target should imply the currently active window's buffer

Implement >FUNC-OR-FUNC-LIST

     This would allow for an ``output translators'', that take a function to modify output with, and a target.  Devise a syntax that works well with pipes, and can accommodate multiple functions (i.e., >'(upcase regexp-quote) or >'upcase).

Allow Eshell to read/write to/from standard input and output

     This would be optional, rather than always using the Eshell buffer. This would allow it to be run from the command line (perhaps).

Write a help command

     It would call subcommands with --help, or -h or /?, as appropriate.

Implement stty in Lisp

Support rc's matching operator, e.g., ~ (LIST) REGEXP

Implement bg and fg as editors of eshell-process-list

     Using bg on a process that is already in the background does nothing.  Specifying redirection targets replaces (or adds) to the list current being used.

Have jobs print only the processes for the current shell

How can Eshell learn if a background process has requested input?

Support 2>&1 and >& and 2> and |&

     The syntax table for parsing these should be customizable, such that the user could change it to use rc syntax: >[2=1].

Allow $_[-1], which would indicate the last element of the array

Make $x[*] equal to listing out the full contents of x

     Return them as a list, so that $_[*] is all the arguments of the last command.

Copy ANSI code handling from term.el into em-term.el

     Make it possible for the user to send char-by-char to the underlying process.  Ultimately, I should be able to move away from using term.el altogether, since everything but the ANSI code handling is already part of Eshell.  Then, things would work correctly on MS-Windows as well (which doesn't have /bin/sh, although term.el tries to use it).

Make the shell spawning commands be visual

     That is, make (su, bash, telnet, rlogin, rsh, etc.) be part of eshell-visual-commands.  The only exception is if the shell is being used to invoke a single command.  Then, the behavior should be based on what that command is.

Create a smart viewing command named open

     This would search for some way to open its argument (similar to opening a file in the Windows Explorer).

Alias read to be the same as open, only read-only

Write a tail command which uses view-file

     It would move point to the end of the buffer, and then turns on auto-revert mode in that buffer at frequent intervals---and a head alias which assumes an upper limit of eshell-maximum-line-length characters per line.

Make dgrep load dired, mark everything, then invoke dired-do-search

Write mesh.c

     This would run Emacs with the appropriate arguments to invoke Eshell only.  That way, it could be listed as a login shell.

Use an intangible PS2 string for multi-line input prompts

Auto-detect when a command is visual, by checking TERMCAP usage

The first keypress after M-x watson triggers
     eshell-send-input

Make / electric

     So that it automatically expands and corrects pathnames.  Or make pathname completion for Pcomplete auto-expand /u/i/std<TAB> to /usr/include/std<TAB>.

Write the pushd stack to disk along with last-dir-ring

Add options to eshell/cat which would allow it to sort and uniq

Implement wc in Lisp

     Add support for counting sentences, paragraphs, pages, etc.

Once piping is added, implement sort and uniq in Lisp

Implement touch in Lisp

Implement comm in Lisp

Implement an epatch command in Lisp

     This would call ediff-patch-file, or ediff-patch-buffer, depending on its argument.

Have an option such that ls -l generates a dired buffer

Write a version of xargs based on command rewriting

     That is, find X | xargs Y would be indicated using Y ${find X}.  Maybe eshell-do-pipelines could be changed to perform this on-thy-fly rewriting.

Write an alias for less that brings up a view-mode buffer

     Such that the user can press SPC and DEL, and then q to return to Eshell.  It would be equivalent to: X > #<buffer Y>; view-buffer #<buffer Y>.

Make eshell-mode as much a full citizen as shell-mode

     Everywhere in Emacs where shell-mode is specially noticed, add eshell-mode there.

Permit the umask to be selectively set on a cp target

Problem using M-x eshell after using eshell-command

     If the first thing that I do after entering Emacs is to run eshell-command and invoke ls, and then use M-x eshell, it doesn't display anything.

M-RET during a long command (using smart display) doesn't work

     Since it keeps the cursor up where the command was invoked.

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