Inputting Rupee symbol (₹) on Linux machines

tl;dr: When using an InScript keyboard layout, press right Alt + 4 to enter the rupee symbol.

One of the things that I couldn’t figure out for a very long time is how to easily enter the Indian Rupee sign (₹) while entering text. When I was using a Linux machine primarily, I managed by simply copy-pasting the symbol whenever I needed it. After using Chrome OS for a few years, I had gotten used to entering the rupee sign without much fuss, and I missed that ease once I returned to a Linux machine.

I started looking around to see how I can modify keyboard layouts to easily enter the rupee sign. To my surprise, all InScript keyboard layouts had this line:

include "rupeesign(4)"

Looking around, I found a /usr/share/X11/xkb/symbols/rupeesign. This file had this config:

xkb_symbols "4" {
    key <AE04>	{ [  NoSymbol,   NoSymbol,   U20B9 ]	};
};

A quick Google search confirmed that U+20B9 was indeed the rupee sign. Basically, everything needed to easily input the rupee sign is there; only I didn’t know how to use this.

The level3 file in the same directory had the clue. This file started with this comment:

// The default behaviour:
// the right Alt key (AltGr) chooses the third symbol engraved on a key.

As soon as I saw the mention of right Alt as the modifier to use, it became clear that right Alt + 4 was all I needed.