CenOS7 设置环境变量

echo $PATH

/usr/local/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/home/java/jdk1.8.0_172/bin:
/home/java/jdk1.8.0_172/jre/bin:/opt/modules/hadoop-3.1.0/bin:/opt/modules/hadoop-3.1.0/sbin:/home/es/.local/bin:/home/es/bin

echo $SHELL
/bin/bash

echo $JAVA_HOME
/home/java/jdk1.8.0_172

env

XDG_SESSION_ID=4
HOSTNAME=bigdata-senior01.home.com
SHELL=/bin/bash
TERM=xterm
HISTSIZE=1000
HADOOP_HOME=/opt/modules/hadoop-3.1.0
SSH_CLIENT=192.168.31.1 52492 22
SSH_TTY=/dev/pts/1
USER=es
JRE_HOME=/home/java/jdk1.8.0_172/jre
。。。

set

BASH=/usr/bin/bash
BASHOPTS=checkwinsize:cmdhist:expand_aliases:extquote:force_fignore:histappend:hostcomplete:interactive_comments:progcomp:promptvars:sourcepath
BASH_ALIASES=()
BASH_ARGC=()
BASH_ARGV=()
BASH_CMDS=()
BASH_LINENO=()
BASH_SOURCE=()
BASH_VERSINFO=([0]="4" [1]="2" [2]="46" [3]="2" [4]="release" [5]="x86_64-redhat-linux-gnu")
BASH_VERSION=‘4.2.46(2)-release‘
CLASS_PATH=.:/home/java/jdk1.8.0_172/lib/dt.jar:/home/java/jdk1.8.0_172/lib/tools.jar:/home/java/jdk1.8.0_172/jre/lib
COLUMNS=113
DIRSTACK=()
DISPLAY=localhost:11.0
EUID=0
GROUPS=()
HADOOP_HOME=/opt/modules/hadoop-3.1.0
...

export

declare -x CLASS_PATH=".:/home/java/jdk1.8.0_172/lib/dt.jar:/home/java/jdk1.8.0_172/lib/tools.jar:/home/java/jdk1.8.0_172/jre/lib"
declare -x DISPLAY="localhost:11.0"
declare -x HADOOP_HOME="/opt/modules/hadoop-3.1.0"
declare -x HISTCONTROL="ignoredups"
declare -x HISTSIZE="1000"
declare -x HOME="/root"
declare -x HOSTNAME="bigdata-senior01.home.com"
declare -x JAVA_HOME="/home/java/jdk1.8.0_172"
declare -x JRE_HOME="/home/java/jdk1.8.0_172/jre"
declare -x LANG="zh_CN.UTF-8"
declare -x LESSOPEN="||/usr/bin/lesspipe.sh %s"
declare -x LOGNAME="es"
... ...

设置一个新的环境变量hello

export HELLO="hello centos7"

echo $HELLO

export设置环境变量只对当前登录的用户环境有效，登出后失效，也就是同一个用户从其他终端登录进来也是无效的，export的效力仅及于该次登陆操作。

declare -x将shell变量输出到环境变量
declare -x hello="hello centos7"

然后用set可以看到hello变量

用env | grep hello 查看

unset hello

env | grep hello 查询不到内容

使用修改 /etc/profile 文件进行环境变量的编辑，是对所有用户有用

vi /etc/profile

#set java environment
JAVA_HOME=/home/java/jdk1.8.0_172
JRE_HOME=/home/java/jdk1.8.0_172/jre
CLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib
PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin
export JAVA_HOME JRE_HOME CLASS_PATH PATH

#set Hadoop environment
export HADOOP_HOME=/opt/modules/hadoop-3.1.0
export PATH=$PATH:$HADOOP_HOME/bin:$HADOOP_HOME/sbin


修改文件后要想马上生效还要运行source /etc/profile不然只能在下次重进此用户时生效

使用修改.bashrc文件进行环境变量的编辑，只对当前用户有用。
在用户目录下的.bash_profile文件中增加变量
vi /home/es/.bash_profile