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# Top 10 reasons why you should be using Eshell
Howard Abrams (he/him)
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While Eshell is this quick and dirty way to run external commands, its
*dirtiness* plays into the Lisp’s *malleable* big ball of mud metaphor,
and I have a number of quick hacks that will make you want to play in
this puddle.
This will be a lightning talk that I will pre-record to show off some
features in eshell I found while diving into the source code … stuff
you can’t do in another terminals. Did you know that \`$$\` is a special
variable that contains the output from the last command?
Update from Howard: I wrote an _expanded transcript_ with more code and functional links. See <http://howardism.org/Technical/Emacs/eshell-why.html>
Want _all_ the code? See my literate dotfiles for #emacs at <https://github.com/howardabrams/hamacs/blob/main/ha-eshell.org>
# Discussion
## Notes
- Full code:
<https://github.com/howardabrams/hamacs/blob/main/ha-eshell.org>
- Longer transcript:
<http://howardism.org/Technical/Emacs/eshell-why.html>
- Yes eshell is usefull! Please help polishing and showing this stuff
you found out.
- Alvaro Ramirez has been doing the DWIM stuff
- Regarding the not so well oiled parts of eshell. There are many
efforts doing a better shell. I have the feeling we already have
that in emacs already and it is just unfinished. But maybe that is
just a statment about emacs in general.
- Reach out to me if anyone wants to pair up and make a eshell-ext
with many of the feature improvements I mentioned in my talk, that
probably shouldn\'t clutter up the default eshell implementation.
## Questions and answers
- Q: Do you fallback to vterm only when needing terminal emulation
(ncurses/etc)? Or are there use cases or contexts where you use
vterm over eshell beyond just terminal emulation needs?
- A: I do vterm mostly for SSH, but Docker builds and Ansible
commands can cause a real mess of the screen, so I often run
those commands in vterm \... but I\'m not really working with
that output.
- Q: One issue I\'ve had with eshell\'s TRAMP integration is that cd
is host agnostic (as you point out). This means typing \`cd\` on a
remote machine will cd back to \$HOME on your local machine. Is
there a way to cd to \$HOME on the remote machine?
- A: It just isn\'t the way it behaves. While Eshell, with a
Tramp-based cd command, will ssh \"under the hood\", it is
temporary, as all the buffer work is local. I usually don\'t
know what will happen, so I often need to switch to vterm for
all ssh work. Which gets me upset when I encounter something
that I would then like to use Eshell for (like piping the output
back to my local Emacs buffer).
- Q: Thank you for the missing Why eshell. Have you thought about
adding it to the eshell manual?
- A: maybe I should team up with someone and improve on it
- Q:Do you know if the eshell {} can be used from elisp? It could make
for a nice elisp shell interface.
- A: Yes. Start with \`eshell-command\' and some variations on
that.
- Q: How does that interplay with your \"literate-devops\" approach,
where things are done in an org buffer/document first instead of
directly in the shell/terminal?
- A: the 2 are different. I use as REPL to test stuff
- Q: Do you have a strategy for getting around eshell\'s lack of
support for input redirection? (I also miss process substitution.)
- A: I have started sending output to Emacs buffers, where I can
have more fun editing them than trying to get a pipe command
sequence working. I wrote a function to pull a buffer back into
Eshell to pipe back to something else. Pipes are problematic in
Eshell.
- Q: Can you call elisp functions as well (ie, not just commands)?
- A: Yes. Functions that start with eshell/ are called as if they
were commands. However, all functions are available in eshell
\... that is what makes it more interesting than the other
comint-based term shells.
- ~~Q: Aren\'t buffers the superior pipes? \--\> that was meant as a
comment when he was asked about pipes, not a question per se \--\>
alright~~
- A:Howard: yes
- Q:Do you have a preferred method for getting argument completion for
shell commands in Eshell?
- A: Check out
<https://github.com/howardabrams/hamacs/blob/main/ha-eshell.org#getopts>
- Q: Similarly, is it possible to get Eldoc-based completion for Elisp
calls in Eshell?
- A: dont know. would be great, though
- Q:Do you have thoughts about
<https://www.masteringemacs.org/article/complete-guide-mastering-eshell#plan-9-smart-shell>
? Summary: it effecitly adds a \"\| less\" to every command so you
get to see paged output if needed, except it is built into eshell.
- A: It is a cool idea, but while I tried it when Mickey first
published that idea, it didn\'t stay in my workflow.
- Q: Is \$\$ a built-in feature of eshell or did you add it?
- A: The Eshell built-in version of \$\$ doesn\'t always work, so
I wrote an updated version that seems to work better (see
<https://github.com/howardabrams/hamacs/blob/main/ha-eshell.org#last-results>)
\... I\'m pretty sure that if you do a command with a lot of
output, it may not work at all, not just get the last of that
output. Mine is just a better hack. :-D
- Q: Do you ever fallback to terminals/shells outside Emacs, and if so
in what circumstances?
- A: I boot up with a Terminal to mount remote file systems, as my
Emacs configuration isn\'t always stored locally on my machine.
I\'ll admit that I sometimes leave the Emacs Garden, but doing
anything interesting become frustrating when you have to leave
the keyboard for the mouse.
- Q: What are the less well-oiled parts of Eshell or edge case issues
that you encounter if any?
- A: We should make a list and start working on them.
- Q:Do you have ways to improve eshell vterm interop like sharing
command history and directory tracking?
- A: I don\'t. If I am going to SSH somewhere, I just start vterm,
and haven\'t thought about any interop.
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