一个while循环

[root@web03 server]# cat .sh
#!/bin/bash

flag=true
a=
b=
while $flag

do

    echo "${a}"
    ((a++))

    while $flag
    do
        echo "$b"
        ((b++))

        if [ ${b} -gt  ]
        then
            flag=false
            echo "${flag}  99999"
        fi
    done

    sleep
done