How does `:w !sudo tee %` work

sudoteevim

If you open a file that you don't have permission to write to in vim, then decide you need to change it, you can write your changes without exiting vim by doing :w !sudo tee %
I don't understand how this can work. Can you please dissect this?
I understand the :w part, it writes the current buffer to disk, assuming there already is a file name associated with it, right?
I also understand the ! which executes the sudo tee command and % represents the current buffer content right?
But still don't understand how this works.

Best Answer

The structure :w !cmd means "write the current buffer piped through command". So you can do, for example :w !cat and it will pipe the buffer through cat.

Now % is the filename associated with the buffer

So :w !sudo tee % will pipe the contents of the buffer through sudo tee FILENAME. This effectively writes the contents of the buffer out to the file.

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Sudo – What Environment is Provided with Sudo?

I don't know about the defaults on Fedora, but on Debian sudo defaults to using the secure_path option with a default value of /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/X11R6/bin.

This means the path is changed to that value every time you use sudo; but when you use sudo -i, the path is changed after that by the root user's RC files.

Vi/vim, how can I write out a number of lines to a new file

You can do

:100,200w filename

Of course 100,200 is the range of lines you want to write.

Best Answer

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