第一种方法
[root@localhost wyb]# cat 11.sh #!/bin/bash#判断给出的字符串是否相等read -p "Please Input a number:" number[ -z $number  ] && echo ‘Input nothing‘ && exit 1len=${#number}a=`echo $number|cut -c 1`for i in `seq $len`do    b=`echo $number|cut -c $i`    [[ "$a" != "$b" ]] && echo no && exitdoneecho yes[root@localhost wyb]# bash 11.sh Please Input a number:1111111122no[root@localhost wyb]# bash 11.sh Please Input a number:1111111yes[root@localhost wyb]# bash 11.sh Please Input a number:666666666yes[root@localhost wyb]# 

第二种方法[root@localhost wyb]# cat 111.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 1a=`echo $number|cut -c 1`b=`echo $number|tr -d $a`[ -z $b ] && echo yes || echo no[root@localhost wyb]# bash 111.sh Please Input a number:111111yes[root@localhost wyb]# bash 111.sh Please Input a number:123445no[root@localhost wyb]# bash 111.sh Please Input a number:66666yes[root@localhost wyb]#