Number pad issues when using a remote 'nano' instance in PuTTY

Question

I'm using PuTTY on an old Windows laptop to communicate with Ubuntu.

When using the terminal, everything is fine and I can use the numpad normally. However, when I open anything in nano, all these keys have functions instead of numbers.

I did a search about this and found a few solutions to change PuTTY settings, but they didn’t have any effect. Is this an issue with PuTTY or with nano?

Answer 1

nano uses the curses keypad function, turning it on (so that curses handles cursor-keys). The terminal description turns on application mode for both the cursor-keys and the numeric keypad, which with PuTTY makes it send the non-numeric stuff.

You could modify the terminal description to remove the numeric-keypad part of the smkx capability:

infocmp -1 >foo
vi foo
... look for smkx=\E[?1h\E=,
... change that to smkx=\E[?1h,
tic foo

Answer 2

For anyone else with this problem—this is PuTTY specific and is caused by the application keypad mode sending escape sequences to nano.

To solve it:

From an open PuTTY terminal:

• Ctrl + right-click to bring up the context menu
• Select "Change Settings..."
• Select Terminal → Features in the left-hand navigation tree
• Check "Disable application keypad mode"

Reference: Description of bug on the Vim (FANDOM.com??) wiki