fossil from source
So … As of this writing, fossil is not in centos/epel, and what is available in ubuntu/lts is way outdated.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