What?

Screenshot

Installation

Archlinux

There's an AUR package:

$ git clone https://aur.archlinux.org/packages/c-lolcat
$ cd c-lolcat
$ makepkg -csi

Fedora

$ dnf install lolcat

Ubuntu (Snap)

See this awesome blog post by a kind person from the internet:

$ snap install lolcat-c

Mac

Build loclcat with:

$ make lolcat

...and put the resulting binary at a place of your choice.

Others

$ make && sudo make install

Why?

This lolcat clone is an attempt to reduce the world's carbon dioxide emissions by optimizing inefficient code. It's >10x as fast and <0.1% as large as the original one.

newton~/d/lolcat <3 dmesg>foo
newton~/d/lolcat <3 time upstream/bin/lolcat foo
13.51user 1.34system 0:15.99elapsed 92%CPU (0avgtext+0avgdata 10864maxresident)k
0inputs+0outputs (0major+1716minor)pagefaults 0swaps
newton~/d/lolcat <3 time ./lolcat foo
0.02user 0.00system 0:00.09elapsed 34%CPU (0avgtext+0avgdata 1936maxresident)k
0inputs+0outputs (0major+117minor)pagefaults 0swaps

Bonus comparison with python-lolcat:

newton~/d/lolcat <3 dmesg>foo
$ time python-lolcat foo
12.27user 0.00system 0:12.29elapsed 99%CPU (0avgtext+0avgdata 11484maxresident)k
0inputs+0outputs (0major+1627minor)pagefaults 0swaps
$ time c-lolcat foo
0.29user 0.00system 0:00.30elapsed 98%CPU (0avgtext+0avgdata 468maxresident)k
0inputs+0outputs (0major+21minor)pagefaults 0swaps

(Read: c-lolcat << python-lolcat << ruby-lolcat)