Shell programming operation and maintenance of written questions

First, to achieve bulk add 10 users, user name user01-10, the password for the user behind with three random characters;

#!/bin/bash
for i in `seq -w 1 10`
do
        user="user$i"
        password=$(cat /dev/urandom | head -1 | md5sum | head -c 3)
        useradd user$i
        echo "$user$password" | passwd --stdin $user
        echo "$user$password" >> userinfo.txt
done

Description:

seq -w 1 10 # generate 10 digits 01, 10 and so on ...

cat / dev / urandom | head -1 | md5sum | head -c 3 # 3 generates random letters or numbers

useradd user # user add command

echo "$ user $ password" | passwd --stdin $ user # password

echo "$ user $ password" >> userinfo.txt # generated user name and password file into userinfo.txt