shelll脚本，常见的脚本题目。

[root@localhost wyb]# cat 2quan.sh
#!/bin/bash

#写一个脚本，先要求输入用户名，然后让他输入一个数字，输的如果是数字给输出yes，不是数字，输出no
#然后如果输入三次以上不是数字锁定此用户，就是不能让他上了
#要求次数累加，即使关了脚本再重启，也没用，依旧锁定，次数到了3就锁定

read_user()
{

read -p "Please Input a Username:" username

}
read_user
while [ -z $username ]
do
    read_user
done

[ ! -f $username.log ] && touch $username.log

judge_user()
{
   key=`cat $username.log|wc -l`
   [ $key -ge  ] && echo "This $username is lock" && exit
}

judge_user
echo 'input `quit`to quit'
while :
do
  judge_user
  read -p "Pleas input a number:" num
   [ -z $num ] && continue
   [[ "$num" = "quit" ]] && break

   expr $num +  &>/dev/null
  [ $? -ne  ] && echo error  >> $username.log && echo no|| echo yes

done
[root@localhost wyb]# bash 2quan.sh
Please Input a Username:cheng
input `quit`to quit
Pleas input a number:eee
no
Pleas input a number:
yes
Pleas input a number:
yes
Pleas input a number:ddd
no
Pleas input a number:aaa
no
This cheng is lock
[root@localhost wyb]# bash 2quan.sh
Please Input a Username:cheng
This cheng is lock
[root@localhost wyb]# bash 2quan.sh
Please Input a Username:jing
input `quit`to quit
Pleas input a number:
yes
Pleas input a number:bbb
no
Pleas input a number:ddd
no
Pleas input a number:aaa
no
This jing is lock
[root@localhost wyb]# bash 2quan.sh
Please Input a Username:quit
input `quit`to quit
Pleas input a number:quit
[root@localhost wyb]# cat jing.log
error
error
error
[root@localhost wyb]# cat cheng.log
error
error
error
[root@localhost wyb]# 

增加了一些需求

#写一个脚本，先要求输入用户名，然后让他输入一个数字，输的如果是数字给输出yes，不是数字，输出no
#然后如果输入三次以上不是数字锁定此用户，就是不能让他上了
#要求次数累加，即使关了脚本再重启，也没用，依旧锁定，次数到了3就锁定
#如果用户被锁，则提示用户问他是不是解锁
#解锁的话需要输入5次数字,有一次错误都不能解锁,如果输入5次都没错,那么用户解锁
#增加注册与登录。如果登录的用户没有注册，则提示注册，如果登录用户已注册，则可以继续操作

[root@localhost wyb]# cat 12quan.sh
#!/bin/bash
read_user()
{
    read -p "Please Input username:" username
}
flag=
read_user
while [ -z $username ]
do
    read_user
done
user_reg()
{
    echo ----------------create a user--------------
    read -p "Please Input A username:" name1
    [ -z $name1 ] && echo "You Do no Input" && exit
    read -p "Please Input A username:" name2
    [ -z $name2 ] && echo "You Do no Input" && exit
    [[ "$name1" = "$name2" ]] && echo $name1 >> user.list
    echo "Your user ($name1) has registered!" && exit  

}
#注册了flag2不变是0可以执行程序
flag2=

[ ! -f ${username}.log ] && touch ${username}.log
[ ! -f  user.list ] && touch user.list
user_exist=`cat user.list|grep -c "\<$username\>"`
[ $user_exist -eq  ] && read -p "You username do not exist.create it(yes/on)?" create_user && flag2=
#[ "$create_user" = "no"  ] && exit
[ $flag2 -eq   ] &&  [[ "$create_user" = "yes"  ]] && user_reg
[ $flag2 -eq  ] && exit
unlock_user()
{
    for i in `seq  - `
    do
        read -p "Please a number(remain $i counts):" unlock_num
        expr $unlock_num +  &>/dev/null
        [ $? -ne  ] && echo "Input error,unlock stop" && exit
    done
    echo "( $username ) has been unlocked"
    > ${username}.log
}
judge_user()
{
    key=`cat ${username}.log|wc -l`
    [ $key -ge  ] && echo "Your username ( $username ) is locked." && flag=
    [ $flag -eq  ] && read -p "Do you wanna to unlock(yes/no)" unlock_key
    [ $flag -eq  ] && [[ "$unlock_key" = "yes" ]] && unlock_user && exit
    [ $flag -eq  ] && [[ "$unlock_key" != "yes" ]] && exit
}
judge_user
echo 'Input `quit` to quit'
while :
do
    judge_user
    read -p "Please Input a number:" number
    [ -z $number ] && continue
    [[ "$number" = "quit" ]] && break

    expr $number +  &>/dev/null
    [ $? -ne  ] && echo "error" >> ${username}.log && echo no || echo yes
done

[root@localhost wyb]# bash 12quan.sh
Please Input username:aaa
You username do not exist.create it(yes/on)?yes
----------------create a user--------------
Please Input A username:aaa
Please Input A username:aaa
Your user (aaa) has registered!
[root@localhost wyb]# bash 12quan.sh
Please Input username:aaa
Input `quit` to quit
Please Input a number:
yes
Please Input a number:
yes
Please Input a number:no
no
Please Input a number:no
no
Please Input a number:no
no
Your username ( aaa ) is locked.
Do you wanna to unlock(yes/no)yes
Please a number(remain  counts):
Please a number(remain  counts):
Please a number(remain  counts):
Please a number(remain  counts):
Please a number(remain  counts):
( aaa ) has been unlocked
[root@localhost wyb]# bash 12quan.sh
Please Input username:aaa
Input `quit` to quit
Please Input a number:
[root@localhost wyb]#