初识脚本

Posted 2020-12-29 jsjobs

1.1 脚本认识

•  1 #!/bin/bash 

第一行，通常用来指定执行脚本的shell ,/bin/bash是CentOS 默认的shell  如果写到第二行，就是注释了

•  1 #!/bin/sh 

这样写也是可以的，sh是bash的软链接，和#!/bin/bash 是没有区别的，理规范的开头使用#!/bin/bash

1.2 查看bash版本

•  1 [[email protected] scripts]# bash --version
   2 GNU bash, version 4.1.2(2)-release (x86_64-redhat-linux-gnu)
   3 Copyright (C) 2009 Free Software Foundation, Inc.
   4 License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
   5  
   6 This is free software; you are free to change and redistribute it.
   7 There is NO WARRANTY, to the extent permitted by law.
   8 [[email protected] scripts]# cat test_1.sh
   9 #!/bin/bash
  10 user=`whoami`
  11 echo $user
  12 [[email protected] scripts]# sh test_1.sh
  13 root
  14 [[email protected] scripts]# ./test_1.sh
  15 root
  16 [[email protected] scripts]# . test_1.sh
  17 root
  18 [[email protected] scripts]# source test_1.sh
  19 root
  20 [[email protected] scripts]# /bin/bash test_1.sh
  21 root
  22 [[email protected] scripts]# /bin/sh test_1.sh
  23 root
  24 [[email protected] scripts]# /server/scripts/test_1.sh
  25 root

   

1.3 书写脚本

 

1.3.1 执行脚本

 

1.3.1.1  小结：

执行脚本的方法有：sh       ./          .           source /bin/bash         /bin/sh pwd/

1.4 继承脚本变量

•  1 [[email protected] scripts]# sh test_1.sh
   2 root
   3 [[email protected] scripts]# echo $user
   4  
   5 [[email protected] scripts]# ./test_1.sh
   6 root
   7 [[email protected] scripts]# echo $user
   8  
   9 [[email protected] scripts]# bash test_1.sh
  10 root
  11 [[email protected] scripts]# echo $user
  12  
  13 [[email protected] scripts]# . test_1.sh
  14 root
  15 [[email protected] scripts]# echo $user
  16 root
  17 [[email protected] scripts]# source test_1.sh
  18 root
  19 [[email protected] scripts]# echo $user
  20 root

1.4.1.1  小结

继承：source 和 .      能继承脚本的变量，其它命令皆不能继承