Day 3 homework

1. Use case Realize the judgment of good and bad grades

vim 1.sh
#!/bin/bash
read -p "please input your score:" score
case $score in
        [0-9]|[1-5][0-9])
                echo "Grade is C"
                ;;
        [6-8][0-9])
                echo "Grade is B"
                ;;
        9[0-9]|100)
                echo "Grade is A"
                ;;
esac
bash 1.sh

2. for establish 20 user

The user prefix is entered by the user

The user's initial password is entered by the user

for example ：test01,test10

vim 2.sh
#!/bin/bash
read -p "pleace input user prefix:" a
read -p "pleace input user postfix:" b
for i in {
    01..20}
do
        user=$a$i
        password=$b$i
        if ! id -u $user &> /dev/null
        then
                useradd $user
                echo $password | passwd --stdin $user &>/dev/null
        else
                echo "user is exist"
        fi
done
bash 2.sh

3. for ping Test refers to the host of the network segment

   The network segment is input by the user , For example, user input 192.168.2 , be ping 192.168.2.10 — 192.168.2.20

   UP： /tmp/host_up.txt

   Down: /tmp/host_down.txt

   vim 3.sh
   #!/bini/bash
   read -p "pleace input ip network segment" a
   for i in {
         2..4}
   do
           ip="$a.$i"
           echo $ip
           if ping -c 2 $ip &>/dev/null
           then
                   echo "$ip is up" >> /tmp/host_up.txt
           else
   
                   echo "$ip is down" >> /tmp/host_down.txt
           fi
   done
   bash 3.sh
   

4. Use for Realize batch host root Password modification

   Success or failure must be recorded

   Tips ： host IP In a file SSH：

   Implement public key authentication , Execute host commands in remote

   Implement public key authentication # ssh-keygen Generate a key pair on the master for management

   ssh-copy-id -i 192.168.2.3

vim 4.sh
#!/bin/bash
ssh-keygen -f /root/.ssh/id_rsa -P '' -q &>/dev/null
for ip in `cat ipfile`
do
  echo $ip
  ssh-copy-copy-id [email protected]$ip
done

for ip in `cat ipfile`
do
  echo $ip
  ssh [email protected] "echo redhat | passwd --stdin root" &>/dev/null
  if [ "$?" -eq 0 ];then
    echo "host $ip successfully update passwd"
  else
    echo "host $ip error update passwd"
  fi
done

bash 4.sh