Linux_Shell 脚本

1. Hello World

vim hello_world.sh

#!/bin/bash
echo "Hello World!"

1.1 输出

chmod +x hello_world.sh

[root@localhost shell]# ./hello_world.sh
Hello World!

2. 检查存活主机

• for循环

  [root@localhost shell]# cat check_hosts.sh

  #!/bin/bash
  #检查主机状态
  for i in {1..254}
  do
        ping -c2 -i0.3 -w1 192.168.1.$i &>/dev/null
        if [ $? -eq 0 ];then
                echo "192.168.1.$i is up."
        else
                echo "192.168.1.$i is down."
        fi
  done

• while循环

  #!/bin/bash
  i=1
  while [ $i -le 254 ]
  do
        ping -c2 -i0.3 -W1 192.168.1.$i &>/dev/null
        if [ $? -eq 0 ];then
                echo "192.168.1.$i is up."
        else
                echo "192.168.1.$i is down."
        fi
        let i++
  done

  3. 猜数字

  [root@localhost shell]# cat guess_num.sh

  
  #!/bin/bash
  num=$[ RANDOM % 100 +1 ]
  while :
  do
        read -p "Enter a num: " cat
        if [ $cat -eq $num ];then
                echo "right!"
                break
        elif [ $cat -le $num ];then
                echo "small!"
        else
                echo "big!"
        fi
  done