jovica

Posted on Sep 11, 2018

The Vim Trick Which Will Save Your Time and Nerves

#vim #sudo

Whether you're beginner or advanced Vim user, I'm sure you've seen this at least once:

E45: 'readonly' option is set (add ! to override)

It usually goes like this:

You open a file with Vim and make some changes. When you try to save the file and see the message above.

Then you realize that you didn’t run Vim with sudo?! Argh, so annoying isn't it?

Today, you're gonna learn how to solve this easily, and once for all.

It's very simple, all you need to do is to add this line to your .vimrc:

cnoremap w!! execute 'silent! write !sudo tee % >/dev/null' <bar> edit!

When you get to the same situation again and you can't save your file, simply run :w!! command, and your changes will be saved!

Now, how this works:

cnoremap - tells Vim that the following mappings that is used when in command-line mode
w!! - the mapping (shortcut) itself.
execute '<command>' - executes a command between the quotes
silent! - run it silently
write !sudo tee % >/dev/null - the magic trick which would take another post to explain
<bar> edit! - this calls the edit command to reload the buffer and then avoid messages such as "the buffer has changed".

Hint: you need to type :w!! fast, so it expands into the full command. Typing these four strings slowly and hitting Enter won't work.

I share tips like this at Mastering Vim Quickly Newsletter.

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Top comments (19)

Braden Best • Sep 11 '18 • Edited

I just use :w !sudo tee % when that happens. I don't come across that situation enough to justify a mapping, and the command is easy to reinvent when needed.

w <file> writes to a file, and can be redirected to an external program's stdin if file is !<command>

sudo tee <file> takes its input and writes it to both stdout and file.

% is vim shorthand for the file open in this buffer.

Btw: sudo -e some_file. Try it.

Supahambition • Sep 11 '18

Or use the chmod command to change the permissions of the file right?
Idk about you guys but I'm not particularly comfortable with running vim through Super User all the time. But maybe that's just being paranoid?

jdnewman85 • Sep 11 '18

This 'trick' alleviates the need to run vim itself as root. Changing permissions is not always preferable. How do you edit system configs? Full blown root user?

Your paranoia has caused you to be less safe...

Ítalo Vieira • Jul 6 '19 • Edited

sudoedit (or sudo -e) is the right way to do when you have not yet open the file with Vim.

vinney cavallo • Sep 11 '18

Sometimes you want the permissions staying the same, but you need the file changed regardless. Maybe this is bad practice, I dunno. Would be curious to hear it discussed by folks who know more than I do.

jovica • Sep 11 '18

hah - thanks :) It's just hardly understandable for beginners in this kind of short form - that's what I had in mind when I mentioned another post.

I didn't test the difference between the /dev/zero and /dev/null, but it shouldn't make a really big difference in this case. Cheers!

Sam Yi • Sep 12 '18

Man though crowd. I like this shortcut. Thanks for posting.

jovica • Sep 14 '18

Haha, thanks :)

Michael Mior • Sep 18 '18

At least on my machine, /dev/zero and /dev/null are the same speed. Even if they were different, I doubt it would be enough to matter unless you were writing a really massive file.

Gnu's Not Unix • Sep 17 '18 • Edited

I use this map:

cnoremap WW w !sudo tee > /dev/null %

However, I prefer to edit files with this alias:

alias svim='sudoedit'

David Castro • Sep 18 '18

Just a warning for anyone that uses this, sudoedit or sudo -e makes a temporary copy of the file and then moves it on top of the real file when the editor exits. Which means that writing your changes doesn't actually modify the file, which caused me much head banging because no matter what I did I'd get the same error since I was making changes that were buffered in sudoedit until I closed my editor, but I was retrying after just writing the change.