====== systemd ======

使用 [[https://wiki.archlinux.org/index.php/Systemd|systemd]] 全家桶。

===== NTP =====

使用 `timedatectl` 开启 NTP 同步服务即可。

<code bash>
timedatectl set-ntp true
</code>

如果想配置 NTP 服务器，可编辑 ''/etc/systemd/timesyncd.conf'' 。可参考：[[linux:ntp|NTP]]

===== timezone =====

设置时区为 +0800

<code bash>
timedatectl set-timezone Asia/Shanghai
</code>

查看可用的时区

<code bash>
timedatectl list-timezones
</code>

===== network =====

使用 ''systemd-networkd'' 替代容易出错的 ''netctl'' ，个人感觉效果还不错，适用于不切换 WiFi 或者使用有线网络的场景。

更多奇怪的用法详见：[[https://wiki.archlinux.org/index.php/Systemd-networkd|systemd-networkd - Archlinux wiki]]

首先使用 ''networkctl list'' 列出网口号，并复制。

==== wired network ====

有线网络的网口号一般以 en 开头，例如 ''enp6s0'' 。

编辑创建配置文件：

<code ini /etc/systemd/network/20-wired.network>
[Match]
Name=enp6s0

[Network]
DHCP=ipv4
</code>

并且重启 ''systemd-networkd'' service 即可生效。

=== 8021X ===

See [[linux:8021x|8021X]].

===== Journal =====

Clean old logs, from [[https://unix.stackexchange.com/questions/139513/how-to-clear-journalctl|stackexchange]]:

<code bash>
# Retain only the past 30 days:

journalctl --vacuum-time=30d
</code>

===== alias =====

<code bash>
# Copy from oh-my-zsh

user_commands=(
  list-units is-active status show help list-unit-files
  is-enabled list-jobs show-environment cat list-timers)

sudo_commands=(
  start stop reload restart try-restart isolate kill
  reset-failed enable disable reenable preset mask unmask
  link load cancel set-environment unset-environment
  edit)

for c in $user_commands; do; alias sc-$c="systemctl $c"; done
for c in $sudo_commands; do; alias sc-$c="sudo systemctl $c"; done
for c in $user_commands; do; alias scu-$c="systemctl --user $c"; done
for c in $sudo_commands; do; alias scu-$c="systemctl --user $c"; done

alias sc-enable-now="sc-enable --now"
alias sc-disable-now="sc-disable --now"
alias sc-mask-now="sc-mask --now"

alias scu-enable-now="scu-enable --now"
alias scu-disable-now="scu-disable --now"
alias scu-mask-now="scu-mask --now"
</code>

===== Reference =====

  * [[https://wiki.archlinux.org/index.php/Systemd-networkd|systemd-networkd - Archlinux wiki]]
  * [[https://wiki.archlinux.org/index.php/Systemd|Systemd - Archlinux wiki]]
  * [[https://xuanwo.io/2019/06/13/switch-to-systemd-networkd/|从 netctl 切换到 systemd-networkd]]