$ ps -u | grep tmux

$ tmux -V
# tmux 1.8

pgrep tmux

lsof -p $tmuxPID | grep REG | grep -i -e deleted -e "tmux$"

/proc/$tmuxPID/exe -V`

for tmuxPID in $(pgrep tmux); do lsof -p $tmuxPID | grep REG | grep -i -e deleted -e "tmux$"; done

for tmuxPID in $(pgrep tmux); do /proc/$tmuxPID/exe -V; done

./tmux2.3 display-message -p "#{version}"

realpath /proc/$(tmux display-message -p "#{pid}")/exe