rhce第一次作业

1.设置一次性计划任务在18：00时关闭系统，并查看任务信息。

[root@server ~]# at 18:00

warning: commands will be executed using /bin/sh

at Wed Nov 20 18:00:00 2024

at> shutdown -h now

[root@server ~]# echo "shutdown -h now" | at 18:00

warning: commands will be executed using /bin/sh

job 3 at Wed Nov 20 18:00:00 2024

2.每周日凌晨2点30分，运行cp命令对/etc/fstab文件进行备份，存储位置为/backup/fstab-YYYY-MM-DD-hh-mm-ss。

[root@server ~]# crontab -e

no crontab for root - using an empty one

crontab: installing new crontab

[root@server ~]# crontab -l

30 2 * * 0 cp /etc/fstab /backup/fstab-$(date +\%Y-\%m-\%d-\%H-\%M-\%S)

3.每周2、4、7的晚上8:45分，备份/var/log/secure文件至/logs目录中，文件名格式为“secure-yyyymmdd”。

[root@server ~]# crontab -e

crontab: installing new crontab

[root@server ~]# crontab -l

30 2 * * 0 cp /etc/fstab /backup/fstab-$(date +\%Y-\%m-\%d-\%H-\%M-\%S)

45 20 * * 2,4,7 /usr/bin/cp /var/log/secure /logs/secure-$(date +\%Y\%m\%d)

4.每两小时取出当前系统/proc/meminfo文件中以S或M开头的行信息追加至/tmp/meminfo.txt文件中。

[root@server ~]# crontab -e

crontab: installing new crontab

[root@server ~]# crontab -l

30 2 * * 0 cp /etc/fstab /backup/fstab-$(date +\%Y-\%m-\%d-\%H-\%M-\%S)

45 20 * * 2,4,7 /usr/bin/cp /var/log/secure /logs/secure-$(date +\%Y\%m\%d)

* */2 * * * grep '^[SM]' /proc/meminfo >> /tmp/meminfo.txt

5.配置ntp时间服务器，确保客户端主机能和服务主机同步时间

①下载

[root@server ~]# yum install chrony -y

Last metadata expiration check: 2:45:42 ago on Tue 19 Nov 2024 07:42:07 PM CST.

Package chrony-4.1-6.oe2203sp4.x86_64 is already installed.

Dependencies resolved.

Nothing to do.

Complete!

②检查存在是否正常开启

[root@server ~]# systemctl start chronyd

[root@server ~]# systemctl enable chronyd

[root@server ~]# rpm -qa | grep chrony

chrony-4.1-6.oe2203sp4.x86_64

[root@server ~]# systemctl is-active chronyd

Active

③编辑chrony.conf允许192.168.244.129/24

[root@server ~]# vim /etc/chrony.conf   #编辑，修改层级位10，允许客户机192.168.122.8

[root@server ~]# systemctl stop firewalld  #关闭防火墙

[root@server ~]# setenforce 0              #暂时关闭selinux

[root@server ~]# systemctl restart chronyd #重启

[root@server ~]# date                      #开始同步

1. [root@client ~]# vim /etc/chrony.conf    # 修改pool 192.168.163.131 iburst
2. [root@client ~]# date                    # 开始同步