So … As of this writing, fossil is not in centos/epel, and what is available in ubuntu/lts is way outdated. So we will obtain the latest. We could of course just download a precompiled binary and use that, or start there to clone the repo, but for giggles we will pull down the source and compile it, in order to use the resulting binary to clone the repo and and build (again) that way. Doing so makes it easier to pull down (and recompile) the updates, but it is also just cool to do this, so why not?

Prerequisites

ubuntu

apt update && apt -y install build-essential zlib1g-dev libssl-dev wget

Grab and build from source

mkdir -p /usr/local/src
cd /usr/local/src
wget http://fossil-scm.org/index.html/uv/fossil-src-2.3.tar.gz
tar zxvf fossil-src-2.3.tar.gz 
cd fossil-2.3/
./configure
make
TMPFOSSIL=`pwd`/fossil

Clone repo and build from there

mkdir -p /usr/local/src/fossils
cd /usr/local/src/fossils/
$TMPFOSSIL clone http://www.fossil-scm.org/fossil fossil.fossil
mkdir fossil
cd fossil
$TMPFOSSIL open ../fossil.fossil 

Following suggestion to build out of tree for easier cleanup

mkdir build
cd build
../configure
make
make install

Updates, later down the road

cd /usr/local/src/fossils/fossil
fossil update trunk
rm -fr build
mkdir build
cd build
../configure
make
make install