全部代码

#!/bin/bash
echo "please input username"
read username
user="cat /etc/passwd | awk -F ':' '{print $1}' | grep '\<$username\>'" 
if [ "$username" == "$user" ]; then
echo "The user exist"
exit 0
fi
echo "please input password"
read password
useradd -d /home/$username $username
echo $password | passwd --stdin $username

为什么这样执行脚本的时候当用户名同名时不会提示The user exist？
而把user改为下文这样就可以了

user=`awk -F : '{print $1}' /etc/passwd | grep "\<$username\>"`