shell脚本应用（5）--实用脚本片断

• 校验参数

1. if [ "$#" -ne 1 ]
2. then
3. echo "Incorrect number of arguments"
4. echo "Usage: command arg1"
5. exit 1
6. fi

• 等待后台程序执行完再继续

1. prog1 &
2. #获取prog1的pid
3. pid1 = $1
4. ...
5. #等待后台prog1执行完继续脚本
6. wait &pid

• 提示用户输入参数

1. #!/bin/bash
2. read -p "please type the password:" PW
3. echo $PW

• 更改登陆用户密码，懒得每次输入新旧密码

1. #!/bin/bash
2. (echo "curpw"; sleep 1; echo "newpw"; sleep 1; echo "newpw") | passwd

• ACM用测试数据检验程序正确与否

1. #！/bin/bash
2. while true
3. do
4. #生成随机变量到input文件中,r能够是生成脚本
5. ./r > input
6. ./a < input > output.a
7. ./b < input > output.b
8. diff output.a output.b
9. if [ $? -ne 0 ]
10. then
11. break
12. fi
13. done