Linux运维工程师面试题总结(6)

dmesg 也是常用来查看系统性能的命令

#题目：有10台被监控主机、一台监控机，在监控机上编写脚本，一旦某台被监控机器/分区适用率大于80%， 就发邮件报警放到crontab里面， 每10分钟检查一次 #测试机器：虚拟机Linux as 4

#1.首先建立服务器间的信任关系。拿两台机器做测试

本机ip:192.168.1.6

[root@codfei ~]# ssh-keygen -t rsa

Generating public/private rsa key pair.

Enter file in which to save the key (/root/.ssh/id_rsa):

/root/.ssh/id_rsa already exists.

Overwrite (y/n)? y (以为我是第2次建立关系所以此处覆盖原来的文件)

Enter passphrase (empty for no passphrase):(直接回车无须输入密钥)

Enter same passphrase again:

Your identification has been saved in /root/.ssh/id_rsa.

Your public key has been saved in /root/.ssh/id_rsa.pub.

The key fingerprint is:

04:37:13:2a:4b:10:af:c1:2b:03:3f:6b:27:ce:b9:62 root@codfei

[root@codfei ~]# cd .ssh/

[root@codfei .ssh]# ll

-rw------- 1 root root 883 Apr 25 17:51 id_rsa

-rw-r--r-- 1 root root 221 Apr 25 17:51 id_rsa.pub

-rw-r--r-- 1 root root 442 Apr 25 17:37 known_hosts

id_rsa是密钥文件，id_rsa.pub是公钥文件。

[root@codfei .ssh]# scp id_rsa.pub192.168.1.4:/root/.ssh/192.168.1.6 root@192.168.1.4's password:

id_rsa.pub 100% 221 0.2KB/s 00:00

这里把公钥文件取名为本机的ip地址就是为了以后和更多的机器建立信任关系不发生混淆。

现在登陆到192.168.1.4机器

[root@codfei ~]# cd .ssh/

[root@codfei .ssh]# cat 192.168.1.6 >> authorized_keys

然后回到192.168.1.6机器直接

[root@codfei .ssh]# ssh 192.168.1.4

Last login: Wed Aug 8 12:14:42 2007 from 192.168.1.6

这样就可以了，里面偶尔涉及到权限问题。一般./ssh文件夹是755 authorized_keys为600或者644

####脚本如下#######################

#!/bin/bash

#SCRIPT:df_check.sh

#Writeen by codfei Mon Sep 3 07:25:28 CST 2007