(a) The first day of the shell

• CentOS default shell version: Bash

  echo $SHELL

• Opening language ID: #!/bin/bash

  在执行bash脚本的时候，内核根据#!解释器来确定改用哪个程序解释这个脚本中的内容

• Script comments

  在shell中，#开头的是注释；

• Execution of Shell scripts

  方式一：bash script-name或sh script-name （推荐使用）方式二：./script-name （当前路径下执行脚本，必须要给执行权限）方式三：source script-name 方式四：cat scritps-name|bash

• Calling a defined variable in the script: no way to use bash script-name, only source script-name can be used to invoke variables in the script

  [[email protected] scripts]# cat test.sh user=`whoami`[[email protected] scripts]# bash test.sh [[email protected] scripts]# echo $user[[email protected] scripts]# source test.sh [[email protected] scripts]# !echoecho $userroot

• The system environment variable library is called in the script

  .  /etc/init.d/functions  

(a) The first day of the shell