1. 編寫指令碼selinux.sh，實現開啟或禁用SELINUX功能。
指令碼如下：

關閉selinux
[[email protected] scripts37]#bash -x selinux.sh

• read -p ‘please input character set selinux for {start|stop} :’ SE
  please input character set selinux for {start|stop} :stop
  ++ sed -rn ‘[email protected]^SELINUX=(.*)@\[email protected]
  ’ /etc/selinux/config
• SEC=enforcing
• ‘[’ stop == start ‘]’
• ‘[’ stop == stop ‘]’
• ‘[’ enforcing == disabled ‘]’
• ‘[’ enforcing == enforcing ‘]’
• sed -ri ‘[email protected]^SELINUX=(.*)@[email protected]’ /etc/selinux/config
• echo ‘selinux stop succeed’
  selinux stop succeed
  開啟selinux
  [[email protected] scripts37]#bash -x selinux.sh
• read -p ‘please input character set selinux for {start|stop} :’ SE
  please input character set selinux for {start|stop} :start
  ++ sed -rn ‘[email protected]^SELINUX=(.*)@\[email protected]’ /etc/selinux/config
• SEC=disabled
• ‘[’ start == start ‘]’
• ‘[’ disabled == enforcing ‘]’
• ‘[’ disabled == disabled ‘]’
• sed -ri ‘[email protected]^SELINUX=(.*)@[email protected]’ /etc/selinux/config
• echo ‘selinux start succeed’
  selinux start succeed
  2、統計/etc/fstab檔案中每個檔案系統型別出現的次數
  grep “^UUID” /etc/fstab | awk -F" " ‘{print $3}’ | uniq -c

3、提取出字串[email protected]%9&Bdh7dq+YVixp3vpw中的所有數字

echo “[email protected]%9&Bdh7dq+YVixp3vpw” | awk ‘{gsub(/[^0-9]/,"",$0);print $0}’

4、解決DOS攻擊生產案例:根據web日誌或者或者網路連線數，監控當某個IP 併發連線數或者短時內PV達到100，即呼叫防火牆命令封掉對應的IP，監控頻 率每隔5分鐘。防火牆命令為:iptables -A INPUT -s IP -j REJECT

將指令碼存到計劃任務中，設定定時任務計劃：

[[email protected] ~]# crontab -e
*/5 * * * * /root/checkip.sh