====== Ubuntu 18/20 相關設定整理 ======
===== 網路 IP 設定 =====
  * 參考 
    - https://www.opencli.com/linux/ubuntu-18-04-netplan-setup-static-ip
    - https://blog.toright.com/posts/6293/ubuntu-18-04-%E9%80%8F%E9%81%8E-netplan-%E8%A8%AD%E5%AE%9A%E7%B6%B2%E8%B7%AF%E5%8D%A1-ip.html
    - https://askubuntu.com/questions/1042582/how-to-set-default-route-with-netplan-ubuntu-18-04-server-2-nic
  * Exp. 更改 IP 設定為 192.168.11.204 <code sh>sudo vi /etc/netplan/00-installer-config.yaml</code><file>
network:
  ethernets:
    ens18:
      addresses: [192.168.11.204/24]
      gateway4: 192.168.11.1
      nameservers:
        addresses: [8.8.8.8,8.8.4.4]
      dhcp4: no
  version: 2
 </file>
  * Exp. 兩張網卡指定 default route 為 eth0 <code sh>sudo vi /etc/netplan/00-installer-config.yaml</code><file>
network:
  ethernets:
    eth0:
      dhcp4: true
    eth1:
      addresses: [192.168.7.101/24]
      routes:
        - to: 192.168.7.0/24
          via: 192.168.7.1
          metric: 40
          table: 200
      nameservers:
         addresses: [8.8.8.8,168.95.192.1]
      dhcp4: no
  version: 2
</file><cli>
localadmin@iiidevops-1:~$ ip route
default via 172.17.13.177 dev eth0 proto dhcp src 172.17.13.189 metric 100
172.17.13.176/28 dev eth0 proto kernel scope link src 172.17.13.189
172.17.13.177 dev eth0 proto dhcp scope link src 172.17.13.189 metric 100
192.168.7.0/24 dev eth1 proto kernel scope link src 192.168.7.101
</cli>
    * 可以透過 sudo netplan apply 立即生效或是 sudo reboot 重新開機後生效

===== 修改 iptables 規則, 重開機仍能自動生效  =====
  * 參考 - https://askubuntu.com/questions/1452706/problem-with-my-iptables-configuration-on-reboot/1452833#1452833
  * 需要安裝 iptables-persistent 套件<cli>
apt install iptables-persistent -y
</cli>
  * 修改 iptables 規則 Exp. <cli>
iptables -I FORWARD -i br0 -p all -j ACCEPT
</cli>
  * 將修改後的規則寫入 /etc/iptables/rules.v4 <cli>
iptables-save -c > /etc/iptables/rules.v4
</cli>
===== 更改 hostname (一) =====
  * 參考 - https://www.itread01.com/content/1541622152.html
  * 先 /etc/cloud/cloud.cfg 內 preserve_hostname 為 true<code sh>sudo vi /etc/cloud/cloud.cfg</code><file>
:
preserve_hostname: true
:
</file>
  * 執行 hostnamectl 設定 hostname Exp. 更改為 pve-devops1<code sh>
sudo hostnamectl set-hostname pve-devops1
</code>

===== 更改 hostname (二) =====
  * Exp. 設定 hostname 為 iServStorM1<code>
sudo su -
vi /etc/hosts
</code><file>
127.0.0.1       localhost
127.0.1.1       iServStorM1
:
</file><code sh>
vi /etc/hostname
</code><file>
iServStorM1
</file><code sh>
hostname -F /etc/hostname
</code>
  * 參考網址 - 
    * http://computer.jges.mlc.edu.tw/index.php/ubuntu/112-ubuntu-14-04-%E8%A8%AD%E5%AE%9Ahostname

===== 建立使用者命令 =====
  * 參考 - https://www.cyberciti.biz/faq/create-a-user-account-on-ubuntu-linux/
  * Exp. 建立 localadmin <cli>
sudo useradd -s /bin/bash -d /home/localadmin/ -m -G sudo localadmin
sudo passwd localadmin 
</cli>

  * 如果useradd 建立時沒提供 sudo 權限可以之後透過 usermod 來處理 Exp.<cli>
sudo usermod -aG sudo localadmin
</cli>

===== 查詢安裝套件檔案路徑 =====
  * 參考網址 - https://www.ubuntu-tw.org/modules/newbb/viewtopic.php?post_id=81494
  * 語法 : dpkg -L 套件名稱 Exp. docker<cli>
/# dpkg -L docker
/.
/usr
/usr/share
/usr/share/doc
/usr/share/doc/docker
/usr/share/doc/docker/changelog.Debian.gz
/usr/share/doc/docker/copyright
</cli>

===== Server 版安裝圖形操作介面 =====
  * <code sh>
sudo apt-get install --no-install-recommends ubuntu-desktop
</code>
  * 參考網址 -
    * http://www.arthurtoday.com/2012/11/ubuntu-server-install-unity-gui.html

===== 清除系統檔案空間 =====
  * System Journal Logs Ref - https://ubuntuhandbook.org/index.php/2020/12/clear-systemd-journal-logs-ubuntu/
    * 查看目前已使用空間 <cli>
root@demo-77:/var/log/journal/4ad9885bb19142118fd758b3be95057e# journalctl --disk-usage
Archived and active journals take up 4.0G in the file system.
</cli>
    * 即時清除保留兩天 <cli>
root@demo-77:/var/log/journal/4ad9885bb19142118fd758b3be95057e# journalctl --rotate
root@demo-77:/var/log/journal/4ad9885bb19142118fd758b3be95057e# journalctl --vacuum-time=2days
:
root@demo-77:/var/log/journal/4ad9885bb19142118fd758b3be95057e# journalctl --disk-usage
Archived and active journals take up 16.0M in the file system.
</cli>
    * 設定最多使用空間 Exp. 500M <cli>
vi /etc/systemd/journald.conf
</cli><file>
:
[Journal]
:
SystemMaxUse=500M
:
</file><cli>
systemctl daemon-reload
</cli>

===== VMWare 內出現的 multipathd 異常訊息 =====
  * 參考 - https://askubuntu.com/questions/1242731/ubuntu-20-04-multipath-configuration
  * 在 VMWare 內建立 Ubuntu 20.04 的 VM , 在 /var/log/syslog 會看到以下的異常訊息<cli>
~# tail -f /var/log/syslog
Aug 31 10:43:07 iiidevops4 multipathd[747]: sda: add missing path
Aug 31 10:43:09 iiidevops4 multipathd[747]: sda: failed to get udev uid: Invalid argument
Aug 31 10:43:11 iiidevops4 multipathd[747]: sda: failed to get sysfs uid: Invalid argument
Aug 31 10:43:12 iiidevops4 multipathd[747]: sda: failed to get sgio uid: No such file or directory
Aug 31 10:43:17 iiidevops4 multipathd[747]: sda: add missing path
</cli>
  * 解決方式 : <cli>
vi /etc/multipath.conf
</cli><cli>
defaults {
    user_friendly_names yes
}
blacklist {
    devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st|sda)[0-9]*"
}
</cli><cli>
systemctl restart multipath-tools
</cli>

{{tag>ubuntu}}