98

When you have to edit system files, it's an usual situation that you launched Emacs with a normal user before, so the file will be write-protected. What can I do to gain root privileges? I mean something like M-x sudo from dired.

I don't want to launch Emacs as super-user and I don't want to quit it.

Improve this question

5 Answers 5

Reset to default
129

Use C-x C-f and type out /su::/etc/hostname or /sudo::/etc/hostname as applicable.

This uses the TRAMP package, which is distributed with Emacs. This package provides access to remote files, and more generally to files that Emacs can't open directly.

Improve this answer
3
  • 5
    Thanks. What is the meaning of the :: ?
    – smonff
    Commented Sep 23, 2014 at 22:29
  • 11
    The : is a separator; we supply it the second time to indicate that there are no more arguments. You can /su:otheruser@localhost:, for instance.
    – artagnon
    Commented Sep 23, 2014 at 22:51
  • 17
    /sudo:: is tramp shorthand for sudo:root@<hostname>:
    – phils
    Commented Oct 6, 2017 at 6:48
14

Use find-file with tramp. At the prompt /sudo::/etc/ssh/ssh_config will use sudo and a subshell to open that file with root privileges. When sudo is first used it will prompt for a password, but until that session closes you can edit any file with those permissions by prefixing with the existing /sudo:: command.

See http://www.gnu.org/software/tramp/ for more details.

Improve this answer
14

There are today many packages that solve this problem (as of 2018). Some of them are:

  • sudo-edit, allows to switch editing rights on an already opened read-only file. Just M-x sudo and type a password and you're done. After many years of use of this one, I think it is the more convenient for this need. sudo-edit allows you to open a file as any user, but it default on sudo if none provided.
  • dired-toggle-sudo. It was the first packaged solution I found after asking this question. It is Dired oriented, so if you prefer the file oriented version, see the first bullet of this list.
  • Other solutions exists on Melpa
Improve this answer
6
  • 1
    M-x sudo works out of the box in doom emacs.
    – Michael Francis
    Commented Apr 2, 2021 at 23:22
  • 1
    @michael-dorst I didn't know despite I am using it ^^
    – smonff
    Commented Apr 4, 2021 at 6:36
  • 1
    For Spacemacs users, SPC f E is the shortcut
    – Benjamin R
    Commented May 2, 2021 at 13:03
  • 2
    In Doom Emacs, use M-x doom/sudo-this-file or SPC f U (M-x sudo didn't exist for me)
    – user37362
    Commented Apr 2, 2022 at 14:37
  • @walnut_salami Doom Emacs doesn't require an extra-package indeed. M-x sudo requires sudo-edit.
    – smonff
    Commented Apr 4, 2022 at 9:48
7

If you use Helm. You don't need any external package / additional config. it works out of the box.

Inside helm-find-files you can invoke find file as root which bound to C-c r. This works for files or directories in helm-find-files session.

If you don't want to type password every time you open root files/dirs. Put the following line to your ~/.authinfo.gpg

machine localhost port sudo login root password xxxxxx
machine your_machine_name port sudo login root password xxxxx

source

Improve this answer
6

If you use the ivy package, and have configured counsel-find-file to replace find-file, then one of the "ivy actions" pre-configured for you already is to edit the file as root. The default hydra keystroke for that action is r.

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.