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## 6 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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