My-MacBook-15:~ seamus$ env
TERM_PROGRAM=Apple_Terminal
SHELL=/bin/bash
TERM=xterm-256color
TMPDIR=/var/folders/8_/s3jxzj5150s9f3d3y5k4wzdr0000gp/T/
Apple_PubSub_Socket_Render=/private/tmp/com.apple.launchd.f9meUexEfE/Render
TERM_PROGRAM_VERSION=421.1
TERM_SESSION_ID=CECBC621-33BB-45FD-96E3-B414DBE99F65
USER=seamus
SSH_AUTH_SOCK=/private/tmp/com.apple.launchd.LVyDWNJZbD/Listeners
PATH=/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Applications/VMware Fusion.app/Contents/Public:/opt/X11/bin
PWD=/Users/seamus
LANG=en_US.UTF-8
XPC_FLAGS=0x0
XPC_SERVICE_NAME=0
SHLVL=1
HOME=/Users/seamus
LOGNAME=seamus
DISPLAY=/private/tmp/com.apple.launchd.tzdryqvBdL/org.macosforge.xquartz:0
SECURITYSESSIONID=186a7
_=/usr/bin/env

My-MacBook-15:~ seamus$ echo $VISUAL

My-MacBook-15:~ seamus$

My-MacBook-15:~ seamus$ VISUAL=nano
My-MacBook-15:~ seamus$ export VISUAL

My-MacBook-15:~ seamus$ export VISUAL=nano

My-MacBook-15:~ seamus$ echo $VISUAL
nano
My-MacBook-15:~ seamus$

My-MacBook-15:~ seamus$ setenv VISUAL

My-MacBook-15:~ seamus$ setenv VISUAL=vi