1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
[[!sidebar content=""]]
[[!meta title="Top 10 reasons why you should be using Eshell"]]
[[!meta copyright="Copyright © 2022 Howard Abrams"]]
[[!inline pages="internal(2022/info/eshell-nav)" raw="yes"]]
<!-- Initially generated with emacsconf-generate-talk-page and then left alone for manual editing -->
<!-- You can manually edit this file to update the abstract, add links, etc. --->
# Top 10 reasons why you should be using Eshell
Howard Abrams (he/him)
[[!inline pages="internal(2022/info/eshell-before)" raw="yes"]]
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.
- eshell is great for running top and htop (except I can't figure out how to input the function keys)
- haha yeah i don't either
- vterm isn't distracting - it has no new features to speak of
## 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.
- Q: Where can I find your eshell/do command? Probably you also have another bunch of interesting Eshell helpers.
- https://gitlab.com/howardabrams/hamacs/-/blob/main/ha-eshell.org?plain=1#L741-761
Other comments from IRC:
- Impressive. eshell is an emacs REPL! I knew I could issue some emacs commands but not this level of interactivity. Thanks!
- The real elisp REPL is ielm, but eshell is more generally useful.
- eshell is a REPL focused on the specific niche of shell. ielm's the pure elisp repl, and it rocks.
- yes. i know ielm. just hadn't realised how powerful eshell is.
- howard-abrams : every time I've watched a talk of yours over the years, Emacs/Org-mode has absorbed one more use cases of mine, and made them be in literate form. I'm down to Emacs and a web browser, so I'm looking ahead to your talk about the Web in Emacs :)
- You can also leverage org-mode source blocks tu turn outputs into inputs to other blocks so, plenty of alternatives to pipes
- Wow! Eshell is awesome! I have just learnt more tips! Thanks howard-abrams!
- I think of Eshell as my *universal* machine REPL, i.e. not just ielm for emacs/elisp nor a shell for the machine, but *both* emacs/elisp and the OS/env.. In that way it's quite neat.
- howard-abrams: thank you, very inspiring! I've always found 'normal' command line usage somewhat cumbersome and am certanly going to look at the code
- I really like eshell but I sometimes find the aliases a bit hard to write. alias f if $* {find-file $1; for i in {cdr {flatten-tree $*}} {find-file-other-window $i}} {echo "No files"} - Should probably use Elisp instead
- I think the aliases are almost completely broken, and only seem to work in the barest of cases.
- Yes, in particular the Lisp part is broken. In combination with $*
- I agree that you should write a function for that. Because as I mentioned in my talk, aliases don't accept $* at all.
- Oh, they do. This alias works. I don't recall the reason why I wrote this as an alias. I probably just wanted to use an alias where possible.
- Huh ... that works? I need to try it out. I couldn't get that working, so that is why I wrote the function that I did.
- watching your talk now; TIL /dev/kill and /devl/clip
[[!inline pages="internal(2022/info/eshell-after)" raw="yes"]]
[[!inline pages="internal(2022/info/eshell-nav)" raw="yes"]]
|
