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My Emacs init file works fine in general. But, if I am in my home directory and if I execute:

pwd

    /home/pedro

sudo emacs /etc/nixos/hosts.nix

For some reason, this opens vanilla Emacs without my init file being loaded. In normal situations, opening a normal file and having vanilla Emacs only happens if I do emacs -q. For instance, emacs -q /home/pedro/Desktop/example.txt.

This gets even weirder for my naive eyes if I change my position on the file structure. After tweaking the position, if I try to open the same file, then Emacs works as expected being loaded with the init file. To illustrate, the following works as expected:

pwd

    /home/pedro

cd /etc/

emacs nixos/hosts.nix

Since this problem might be related to my OS, I must say that I am using NixOS. This is my configuration file.

This does not seem to be the same situation as this previous question. On the previous question, the person was unable to do a sudo emacs. I can always do it, but in a specific case, my init file is not been loaded.

Why does this happen?

Is there some way to do sudo emacs /etc/host being on home and with my init file being loaded?

Pedro Delfino
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    When you open emacs as a super user, it tries to get the init file of that user. Since there's none, it starts vannila emacs. I suggest opening emacs as a normal user and opening a buffer with super user privileges, by using tramp. – aadcg May 13 '22 at 15:10
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    Does this answer your question? ["sudo emacs" Doesn't Work](https://emacs.stackexchange.com/questions/21454/sudo-emacs-doesnt-work) – Tyler May 13 '22 at 17:31

2 Answers2

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sudo starts a session where the user is root, not you. It is looking for an init file under the home directory of root (usually /root on GNU Linux). It looks in the usual places (/root/.emacs, /root/.emacs.d/init.el etc) and if it doesn't find any, it will start a vanilla emacs session (as @aadcg points out in a comment).

Try

sudo emacs --user pedro ...

to run emacs with an arbitrary user's init file. See the man page of emacs with M-x man RET emacs for all the options.

Depending on how you set up your load-path however, you might have problems: e.g. I use $HOME in my load-path to pick up several libraries, but that expands to /root in the sudo session, so those libraries are not found. One way is to symlink /root/libdir to /home/pedro/libdir in such cases, one symlink per library directory. Another way is to reorganize your init file to not use $HOME. A third way is to provide a /root/.emacs that sets some things up and then loads your init file with (load "/home/pedro/.emacs.d/init.el") or similar - the setting up I mention would provide impedance matching between the root environment and whatever your init file requires.

In general however, it's not a particularly good idea to be running emacs (or a shell) as root: too many opportunities to really damage your system. sudo should be used for targeted operations that have to be done as root.

@aadcg in another answer provides a function that uses tramp to create a "sudo-ed" buffer for the same file. I use tramp directly to do the same thing without the function, but it amounts to the same thing.

I sometimes don't bother with tramp: to edit a file as root, I do sudo ed <file>, running the ancient line editor as root under a command shell within emacs no less, causing untold amounts of mirth for anyone watching :-)

NickD
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4

@NickD solves the issue from one perspective. There's another way to go about it.

Open emacs without sudo and, whenever you need root privileges to edit a file, use the following command:

(defun my-sudo ()
    "Use Tramp to sudo the current buffer."
    (interactive)
    (when buffer-file-name
      (find-alternate-file (concat "/sudo:root@localhost:" buffer-file-name))))
aadcg
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