Install i3-gaps on ubuntu 18.04

i3-gaps.sh

#!/bin/bash
sudo apt install -y libxcb1-dev libxcb-keysyms1-dev libpango1.0-dev libxcb-util0-dev libxcb-icccm4-dev libyajl-dev libstartup-notification0-dev libxcb-randr0-dev libev-dev libxcb-cursor-dev libxcb-xinerama0-dev libxcb-xkb-dev libxkbcommon-dev libxkbcommon-x11-dev autoconf libxcb-xrm0 libxcb-xrm-dev automake

cd /tmp

# clone the repository
git clone https://www.github.com/Airblader/i3 i3-gaps
cd i3-gaps

# compile & install
autoreconf --force --install
rm -rf build/
mkdir -p build && cd build/

# Disabling sanitizers is important for release versions!
# The prefix and sysconfdir are, obviously, dependent on the distribution.
../configure --prefix=/usr --sysconfdir=/etc --disable-sanitizers
make
sudo make install

Note that I had to checkout a different branch for gaps to work. Master is on i3 4.14, and 4.15 or greater is apparently needed for gaps to work. I checked out the 4.17 branch.

Agreed, please add it to the script, I was having a rough time until I checked out on 4.18.3 branch (last with a configure.ac file)

help me autoreconf: 'configure.ac' or 'configure.in' is required

Together, all of these comments result in these commands:

sudo apt install -y libxcb1-dev libxcb-keysyms1-dev libpango1.0-dev libxcb-util0-dev libxcb-icccm4-dev libyajl-dev libstartup-notification0-dev libxcb-randr0-dev libev-dev libxcb-cursor-dev libxcb-xinerama0-dev libxcb-xkb-dev libxkbcommon-dev libxkbcommon-x11-dev autoconf libxcb-xrm0 libxcb-xrm-dev automake i3status suckless-tools libxcb-shape0-dev
git clone https://www.github.com/Airblader/i3 i3-gaps
cd i3-gaps/
git checkout 4.18.3
autoreconf --force --install
rm -rf build/
mkdir -p build
cd build/
../configure --prefix=/usr --sysconfdir=/etc --disable-sanitizers
make
sudo make install