instalar i3 ubuntu 18.04

$ /usr/lib/apt/apt-helper download-file https://debian.sur5r.net/i3/pool/main/s/sur5r-keyring/sur5r-keyring_2019.02.01_all.deb keyring.deb SHA256:176af52de1a976f103f9809920d80d02411ac5e763f695327de9fa6aff23f416
# dpkg -i ./keyring.deb
# echo "deb https://debian.sur5r.net/i3/ $(grep '^DISTRIB_CODENAME=' /etc/lsb-release | cut -f2 -d=) universe" >> /etc/apt/sources.list.d/sur5r-i3.list
# apt update
# apt install i3

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$ sudo add-apt-repository ppa:jonathonf/i3
$ sudo apt-get update
$ sudo apt-get install i3