生命周期只在你当前终端有效

用来添加一个新的环境变量

export TEST_ENV='test_enviroment'
evn
	

// 输出可以看到多了 TEST_ENV

TERM_PROGRAM=Apple_Terminal
SHELL=/bin/bash
TERM=xterm-256color
TMPDIR=/var/folders/7n/5z1svm_n0nndw5vqdct3kh940000gn/T/
Apple_PubSub_Socket_Render=/private/tmp/com.apple.launchd.znQyJYjsql/Render
TERM_PROGRAM_VERSION=361.1
TERM_SESSION_ID=49EE5104-9974-4515-8CA2-8A19D32250FB
USER=zengfeng
SSH_AUTH_SOCK=/private/tmp/com.apple.launchd.EHX84vGXeo/Listeners
__CF_USER_TEXT_ENCODING=0x1F5:0x19:0x34
PATH=/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/git/bin:/usr/local/mysql/bin/:/Applications/adt-bundle-mac-x86_64-24/sdk/platform-tools:/Applications/adt-bundle-mac-x86_64-24/sdk/tools:/usr/local/local:
PWD=/usr/local/bin
LANG=zh_CN.UTF-8
XPC_FLAGS=0x0
XPC_SERVICE_NAME=0
SHLVL=1
HOME=/Users/zengfeng
TEST_ENV=test_enviroment // 多了这条
LOGNAME=zengfeng
_=/usr/bin/env

用来设在PATH

export PATH=$PATH:/Users/zengfeng/workspaces/bin
echo $PATH

// 输出

	PATH=/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/git/bin:/usr/local/mysql/bin/:/Applications/adt-bundle-mac-x86_64-24/sdk/platform-tools:/Applications/adt-bundle-mac-x86_64-24/sdk/tools:/usr/local/local::/Users/zengfeng/workspaces/bin