~ $ sw_vers -productVersion
10.12

~ $ brew --version
Homebrew 1.0.8
Homebrew/homebrew-core (git revision f9a5; last commit 2016-10-22)

~ $ brew update; and brew upgrade
Already up-to-date.

~ $ type tmux
type: Could not find 'tmux'

~ $ brew install tmux
==> Downloading https://homebrew.bintray.com/bottles/tmux-2.3_1.sierra.bottle.tar.gz
######################################################################## 100.0%
==> Pouring tmux-2.3_1.sierra.bottle.tar.gz
==> Caveats
Example configuration has been installed to:
  /usr/local/opt/tmux/share/tmux

Bash completion has been installed to:
  /usr/local/etc/bash_completion.d
==> Summary
/usr/local/Cellar/tmux/2.3_1: 10 files, 652.4K

~ $ tmux -V
tmux 2.3

~ $ tmux
can't create socket: No such file or directory

~ $ mktemp -d /tmp/tmux-XXXX
/tmp/tmux-Kxsn
~ $ tmux -S /tmp/tmux-Kxsn/sock