Within vi if you can't exit /etc/vim/vimrc you can type
And to turn it back on:
Many of us have a dark/black background in our terminal/shell making the default syntax unreadable, the solution is to either turn off syntax highlighting with :syntax off or to enable a special option in /etc/vim/vimrc
The "syntax on" enables the highlighting permanently, and "syntax off" turn it off permanently (but of course it can temporarily be enabled or disabled within vi as shown above).
" If using a dark background within the editing area and syntax highlighting
" turn on this option as well
If you are using a dark background then also set the "set background=dark" option on, otherwise it makes everything unreadable. I struggled with this until realizing that was an option.
You can also run "set background=dark" from vi itself.
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