我的系统改了也不行，还把 pacman.conf 文件改乱了。。。以后改重要文件是一定要先备份 cp foo foo.bak

这里贴一个范例，供改坏之后参考：

[options]
NoUpgrade = etc/passwd etc/group etc/shadow
NoUpgrade = etc/fstab
Architecture = x86_64

[core]
SigLevel = PackageRequired
Include = /etc/pacman.d/mirrorlist

[extra]
SigLevel = PackageRequired
Include = /etc/pacman.d/mirrorlist

#[community-testing]
#SigLevel = PackageRequired
#Include = /etc/pacman.d/mirrorlist

[community]
SigLevel = PackageRequired
Include = /etc/pacman.d/mirrorlist

# 如果打算在 x86_64 系统上运行32位软件，启用 multilib 软件仓库。

#[multilib-testing]
#SigLevel = PackageRequired
#Include = /etc/pacman.d/mirrorlist

#[multilib]
#SigLevel = PackageRequired
#Include = /etc/pacman.d/mirrorlist

# 自定义软件仓库实例，如何创建软件仓库参见 pacman man手册页。
#[custom]
#SigLevel = Optional TrustAll
#Server = file:///home/custompkgs

[archlinuxcn]
SigLevel = Optional TrustedOnly
Server = http://repo.archlinuxcn.org/$arch

解决方法：

最后看到了这个帖子，救命贴 :P, 得到解决办法如下：

 rm -R  /etc/pacman.d/gnupg/      # 删除gnupg目录及其文件
 pacman-key --init
 pacman-key --populate archlinux
 pacman-key --populate archlinuxcn    # 启用了archlinux中文软件库的还要执行这个

更新，升级，妥妥的 ：）

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