How to change user using tramp?
reddit / emacs

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BlackberryPerfect938 · 2022-09-18 07:20

I have server which connect using ssh, my ssh configuration denies
root user and only allows connection via my admin user with ssh key.
For each service i made a separate user which only he and admin can
access service related files. Question is how to i access (read/write)
files as other user? I know i can use eshell and switch users using my
shell like this "su - user4" but how to i do this using C-x C-f?

If my question is unclear please point it out in a comments. Thanks :)

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podtatranec · 2022-09-18 07:36

I guess you are looking for https://www.gnu.org/software/emacs/manual/
html_node/tramp/Multi_002dhops.html?

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[deleted] · 2022-09-18 07:36

[deleted]

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BlackberryPerfect938 · 2022-09-18 07:58

Yea, that seems pretty close to what i want, tho i'm going to be
honest i'm trying to understand how to use this `tramp-default-
proxies-alist` list to change users in remote ssh session.

I found this dired syntax works for me: `C-x C-f
/ssh:ipaddress|sudo:user4@ipaddress:`

user4 - being user that i want to switch to

ipaddress - being, well. my servers public ip
address in my case

Tho i dont understand why i need to retype ipaddress a second time,
thats pretty cumbersome.

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BlackberryPerfect938 · 2022-09-18 08:38

Also another question, when i am connected to ssh session in eshell
why i cant do this:

`ps aux | grep 'pattern'` for example?

I researched about eshell a bit and i know that eshell sometimes uses
it's own lisp commands that replace built-in commands, to invoke
built-in command you have to prefix it with \*

from: [https://www.gnu.org/software/emacs/manual/html\_mono/eshell.htm
l](https://www.gnu.org/software/emacs/manual/html_mono/eshell.html)
section: 2.3 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

Typing this `which grep` outputs: `eshell/grep is a byte-compiled Lisp
function in ‘em-unix.el’.` so i should use *grep to invoke built-in
command

But this `ps aux | *grep pattern` also does not work. What did i do
wrong here?

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xtifr · 2022-09-18 09:26

Doesn't `/ssh:user4@ipaddress:` work? You can't get root that way,
since ssh won't allow direct root logins, but for a normal user
account, that's not a problem.

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BlackberryPerfect938 · 2022-09-18 09:50

i should have specified that user4 is not admin user. in my
configuration i can only access point - though admin user (not root
user, just user with sudo privileges, cause i guess it's more secure
this way) , so yea /ssh:adminuser@ipaddress should work. however if i
do \`ssh user4@ipadress\` i get Permission denied.

> For each service i made a separate user

user4 is just one of those "service users"

Sorry i'm really bad at explaining stuff ):

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7890yuiop · 2022-09-18 14:43

> Tho i dont understand why i need to retype ipaddress a second time,
thats pretty cumbersome.

If you're using a version of Emacs older than 27.1, failing to
explicitly specify the remote hostname for each hop will cause bad
behaviours that you don't want (`sudo:user4@localhost:` would get
proxied to your `ipaddress` host -- a problem which is worse if,
instead of `user4`, it's `root` and `sudo::`).

That got fixed, so if you're using Emacs 27.1 or later then I think
you can safely use this:

    /ssh:ipaddress|sudo:user4@:

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mmaug · 2022-09-18 14:54

Eshell doesn't support the shell pipe (|)

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BlackberryPerfect938 · 2022-09-18 14:58

Wow it DID get fixed! nice :)

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BlackberryPerfect938 · 2022-09-18 15:02

Oh that's unfortunate ):

I did test `*ls | *grep pattern` and `ls | grep patter` and both
worked so it seemed to me like pipes did work in eshell. I guess pipes
are just not fully functional in eshell?