#vi直接调用vim
echo "alias vi='vim'" >>/etc/profile
tail -1 /etc/profile
source /etc/profile
#！/bin/bash
head -1 /etc/init.d/sshd
cat /etc/redhat-release
加载顺序通常是/etc/profile、～/.bash_profile、～/.bashrc、/etc/bashrc
chmod u+x test.sh
环境变量，比如HOME、PATH、SHELL、UID、USER
export MAVEN_HOME=/usr/local/apache-maven-3.5.3
export JAVA_HOME=/usr/local/jdk1.8.0_172
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
#当天
NOWDATE=$(date +%F)
echo $(date +%F).tar.gz
echo `date +%F`.tar.gz
#主机名
uname -n
hostname
#awk正确输出
awk 'BEGIN {print "'$ETT'"}'
