shell脚本，判断给出的字符串是否相等。

第一种方法
[root@localhost wyb]# cat .sh
#!/bin/bash
#判断给出的字符串是否相等

read -p "Please Input a number:" number
[ -z $number  ] && echo 'Input nothing' && exit 

len=${#number}
a=`echo $number|cut -c `
for i in `seq $len`
do
    b=`echo $number|cut -c $i`
    [[ "$a" != "$b" ]] && echo no && exit

done
echo yes
[root@localhost wyb]# bash .sh
Please Input a number:
no
[root@localhost wyb]# bash .sh
Please Input a number:
yes
[root@localhost wyb]# bash .sh
Please Input a number:
yes
[root@localhost wyb]# 

第二种方法
[root@localhost wyb]# cat .sh
#!/bin/bash
#判断给出的字符串是否相等

read -p "Please Input a number:" number
[ -z $number ] && echo 'Input nothing' && exit 

a=`echo $number|cut -c `
b=`echo $number|tr -d $a`
[ -z $b ] && echo yes || echo no
[root@localhost wyb]# bash .sh
Please Input a number:
yes
[root@localhost wyb]# bash .sh
Please Input a number:
no
[root@localhost wyb]# bash .sh
Please Input a number:
yes
[root@localhost wyb]#