constantly flashing bright green while typing

If the trailing-whitespace highlighting annoys you, you can edit /usr/share/nano/sh.nanorc and remove or comment out the line that says: color ,green "[[:space:]]+$". Problem solved. (You will then probably want to do the same for the other *.nanorc files there.)

Why would this flashing behaviour ever be a desirable default?

On 26/03/15 01:12, Benno Schulenberg wrote:
> If the trailing-whitespace highlighting annoys you, you can edit
> /usr/share/nano/sh.nanorc and remove or comment out the line that says:
> color ,green "[[:space:]]+$". Problem solved. (You will then probably
> want to do the same for the other *.nanorc files there.)
>

Code is inspected far more often than it is written, and when inspecting code, some people do want to be alerted to trailing whitespace. So that's why it is in several of the *.nanorc files. However, those files in /usr/share/nano are just examples -- they are meant to be customized by the user. Most distributions, however, include and activate them by default.

By the way, it is not necessary to edit the files in /usr/share/nano; you can instead redefine any syntax in your ~/.nanorc: just put in 'syntax "sh" "\.sh$"' and follow it by the color commands that you do want.

(In newer nanos (2.4.0 and higher) there is no need to completely redefine a syntax; you can just add or override things with 'extendsyntax'. In your case you would put 'extendsyntax sh color black, "[[:space:]]+$"' to get rid of the trailing-whitespace colouring.)

If, when reading code, you do want trailing whitespace to be highlighted, you can just toggle syntax colouring off with Alt+Y while you are typing the code, and toggle it back on when you are done writing.

Okay, all that is selfhelp. But if you think that for most people the colouring of trailing whitespace should never be the default, you could report a bug to nano itself (https://savannah.gnu.org/bugs/?group=nano) or send an email to its development list (https://lists.gnu.org/mailman/listinfo/nano-devel).

I'm not against the highlighting of trailing whitespace, most of the time i do actually want to be notified of it. The problem is that the syntax highlighting code considers all spaces to be "trailing whitespace" while the user is typing them. It's like a bell going off every time you press the spacebar.

I have no idea if it's possible to specify "don't complain about trailing whitespace when the cursor is at the end of the line", but if it is that seems like it would be the best solution. That way it wouldn't complain about spaces while typing, but after going on to the next line if there were still trailing spaces it would correctly complain.

Nano colours the things on the screen using just the regular expressions specified in the relevant syntax file. There is no way that these regexes can take the position of the cursor into account. (Well, not without a major and ugly patch, and that for just one special case.) So... unless you are willing to write the patch...