概述

shell是一个命令解释器，是一个程序/bin/bash,解释linux的命令,而shell脚本是一系列的命令组成的文件，想要熟练掌握shell脚本，唯有不断练习，接触各种各样的需求并用shell来实现才可以。

需求

利用case语句编写脚本，满足下列要求

1.执行create时根据userfile和passfile建立用户

2.执行delete时根据userfile删除用户

1、脚本内容：

# vim user_ctrl.sh
#!/bin/bash
read -p "Please input the operation (create or delete ): " OPERATION 
//输入你要执行的动作
case $OPERATION in
 create) //第一种情况：create
 read -p "Please input the userfile : " USERFILE //提示输入文件
 [ -e $USERFILE ] || { //判断是否存在
 echo "$USERFILE is not exist "
 exit 1
 }
 read -p "Please input the passwdfile ： " PASSFILE
 [ -e $PASSFILE ] || {
 echo "$PASSFILE is not exist "
 exit 1
 }
 USERLINE=`awk 'BEGIN{N=0}{N++}END{print N}' $USERFILE` //计算userfile文件行数
 for LINE_NUM in `seq 1 $USERLINE` //利用循环建立
 do
 USERNAME=`sed -n "${LINE_NUM}p" $USERFILE` //截取userfile文件第一行内容
 PASSWORD=`sed -n "${LINE_NUM}p" $PASSFILE` //截取passfile文件第一行内容
 useradd $USERNAME //建立用户
 echo $PASSWORD | passwd --stdin $USERNAME
 done
 ;;
 delete) //第二种情况：delete
 read -p "Please input the userfile ： " USERFILE
 [ -e $USERFILE ] || {
 echo "$USERFILE is not exist "
 exit 1
 }
 USERLINE=`awk 'BEGIN{N=0}{N++}END{print N}' $USERFILE`
 for LINE_NUM in `seq 1 $USERLINE`
 do
 USERNAME=`sed -n "${LINE_NUM}p" $USERFILE`
 userdel -r $USERNAME
 done
 ;;
 *) //第三种情况：其余各种情况
 echo Error!
 ;;
esac

2、执行：

[root@localhost mnt]# cat userfile 
user1
user2
user3
[root@localhost mnt]# cat passfile 
123
456
789
[root@localhost mnt]# sh user_ctrl.sh user 
Please input the operation (create or delete ): hello //输入错误动作
Eorror!
[root@localhost mnt]# sh user_ctrl.sh user 
Please input the operation (create or delete ): create
Please input the userfile : user //输入错误文件
user is not exist 
[root@localhost mnt]# sh user_ctrl.sh user 
Please input the operation (create or delete ): create
Please input the userfile : userfile
Please input the passwdfile ： passfile //建立用户
Changing password for user user1.
passwd: all authentication tokens updated successfully.
Changing password for user user2.
passwd: all authentication tokens updated successfully.
Changing password for user user3.
passwd: all authentication tokens updated successfully.
[root@localhost mnt]# sh user_ctrl.sh user 
Please input the operation (create or delete ): delete //删除用户
Please input the userfile ： userfile
[root@localhost mnt]# id user1
id: user1: no such user

关于shell脚本就介绍到这了，大家在看需求的时候建议自己先写一下，然后再对着改进，效果会好一点。后面小编会分享更多linux方面内容，感兴趣的朋友走一波关注哩~