How do I set vim as the default editor when I sudo?

Question

I'm working on a CentOS 5.9 machine, and I simply want to type

sudo vi somefile

and have my trusty vim with syntax highlighting, etc. This seems simple enough, but after many attempts, it's still not working.

root@localhost> which vi
alias vi='vim'
        /usr/bin/vim
root@localhost> sudo which vi
/bin/vi
root@localhost> sudo -i which vi
/bin/vi
root@localhost> sudo -E which vi
/bin/vi

I logged in as root to ensure that by default vi somefile invoked vim. It did. I also tried to preserve the environment with -E and run the login scripts with -i. That did not work. In both my .profile and /etc/environment, I export the EDITOR as vim, and set vi as an alias to vim.

I also commented out a env_reset line in /etc/sudoers.

What else should I try? I didn't think replacing vi with vim would be so difficult, and I really like to understand what is going on here.

Answer 1

That's what the command sudoedit is for. It creates a temporary copy that is edited in the users environment. It consults SUDO_EDITOR, VISUAL and the variable EDITOR to find a suitable binary. After the edit the copy overwrites the original file.

Answer 2

In case you always want to use vim instead of vi, you can just

$ sudo ln -s /usr/bin/vim /usr/local/bin/vi

(This assumes you have /usr/local/bin before /bin in your PATH.)

Granted, it's a (system-local) hack, but quite simple and effective.

Answer 3

I believe that the reason for the observed behavior may be found in the PATH variable. It is possible that as a regular logged-in user the segment /usr/bin comes before /bin, while when sudoing as root, the segment /bin comes before /usr/bin.

If so, the difference can be traced to either one or both of the following origins. If the value of PATH is different when using sudo, this points to the secure_path configuration parameter, typically set in /etc/sudoers or one of the /etc/sudoers.d/* files. However, if the value of PATH is different when logged-in as root (whether a first-level login or with sudo's -i/--login switch), this points to a startup file such as /etc/{profile,profile.d/*} and /etc/{bashrc,bash_*}.

I don't have a CentOS 5 installation handy, but my Alma 8 server gives the following:

## As a regular logged-in user
$ echo $PATH
/home/me/.local/bin:/home/me/bin:/usr/local/bin:/usr/bin:/usr/local/sbin:/usr/sbin

## Sudoing as root (notice the reverse order)
$ sudo bash -c 'echo $PATH'           
/sbin:/bin:/usr/sbin:/usr/bin

## Sudoing as myself (same value)
$ sudo -u me bash -c 'echo $PATH'
/sbin:/bin:/usr/sbin:/usr/bin

## Indeed...
$ sudo grep secure_path /etc/sudoers
Defaults    secure_path = /sbin:/bin:/usr/sbin:/usr/bin

You might also give a quick glance at sudo's env_keep parameter and add VISUAL and EDITOR to the list of kept variables if not already there, but since you mentioned that env_reset was turned off, it probably won't change much.