Install TMUX on MacOS without Brew

install_tmux_macos_no_brew.sh

#!/bin/sh

## setup _________________________________

TMUX_VER=2.9a
LIBEVENT_VER=2.1.11-stable
TEMP_COMPILE=~/tmux-temp-compile
COMMON_INSTALL_PREFIX=/opt
SYMLINK=/usr/local/bin/tmux

## _______________________________________

echo
echo ">>> Creating and using temporary dir ${TEMP_COMPILE} for downloading and compiling libevent and tmux ..."
echo

mkdir ${TEMP_COMPILE}
cd ${TEMP_COMPILE}

echo
echo ">>> Downloading the releases ..."
echo

curl -OL https://github.com/tmux/tmux/releases/download/${TMUX_VER}/tmux-${TMUX_VER}.tar.gz
curl -OL https://github.com/libevent/libevent/releases/download/release-${LIBEVENT_VER}/libevent-${LIBEVENT_VER}.tar.gz

echo
echo ">>> Extracting tmux ${TMUX_VER} and libevent ${LIBEVENT_VER} ..."
echo

tar xzf tmux-${TMUX_VER}.tar.gz
tar xzf libevent-${LIBEVENT_VER}.tar.gz

echo
echo ">>> Compiling libevent ..."
echo

cd libevent-${LIBEVENT_VER}
./configure --prefix=${COMMON_INSTALL_PREFIX}
sudo make
sudo make install

echo
echo ">>> Compiling tmux ..."
echo

cd ../tmux-${TMUX_VER}
LDFLAGS="-L${COMMON_INSTALL_PREFIX}/lib" CPPFLAGS="-I${COMMON_INSTALL_PREFIX}/include" LIBS="-lresolv" ./configure --prefix=${COMMON_INSTALL_PREFIX}
make
echo
echo ">>> Installing tmux in ${COMMON_INSTALL_PREFIX}/bin ..."
echo

sudo make install

echo
echo ">>> Symlink to it from ${SYMLINK} ..."
sudo ln -sf ${COMMON_INSTALL_PREFIX}/bin/tmux ${SYMLINK}

echo
echo ">>> Cleaning up by removing the temporary dir ${TEMP_COMPILE} ..."
echo

cd ..
sudo rm -rf ${TEMP_COMPILE}

The script is based on this one, updated with externalized setup variables and more verbosity mainly.
I just ran it again now on a brand new MacOS, before posting here, to make sure it works flawlessly.

> sw_vers
ProductName:	Mac OS X
ProductVersion:	10.15.2
BuildVersion:	19C57
>