我在使用 pacman 安装软件包时遇到问题
首先正确更新 pacman，pacman -Syu没有任何问题，
但是，当尝试安装时，响应sudo如下pacman -S sudo：
[root@cx-W55xEU /]# pacman -S sudo
resolving dependencies...
looking for conflicting packages...
Packages (1) sudo-1.8.17.p1-1
Total Download Size: 0.90 MiB
Total Installed Size: 3.73 MiB
:: Proceed with installation? [Y/n] y
error: could not open file: /etc/mtab: No such file or directory
error: could not determine filesystem mount points
error: failed to commit transaction (unexpected error)
Errors occurred, no packages were upgraded.
filesystem阅读完相关内容后，我尝试安装可以pacman -S filesystem解决问题的软件包mtab。
[root@cx-W55xEU /]# pacman -S filesystem
warning: filesystem-2015.09-1 is up to date -- reinstalling
resolving dependencies...
looking for conflicting packages...
Packages (1) filesystem-2015.09-1
Total Installed Size: 0.01 MiB
Net Upgrade Size: 0.00 MiB
:: Proceed with installation? [Y/n] y
(1/1) checking keys in keyring [####################################################] 100%
error: GPGME error: Invalid crypto engine
(1/1) checking package integrity [####################################################] 100%
error: GPGME error: Invalid crypto engine
error: filesystem: missing required signature
:: File /var/cache/pacman/pkg/filesystem-2015.09-1-x86_64.pkg.tar.xz is corrupted (invalid or corrupted package (PGP signature)).
Do you want to delete it? [Y/n] y
error: failed to commit transaction (invalid or corrupted package (PGP signature))
Errors occurred, no packages were upgraded.
删除后，我重新尝试下载最新版本并pacman -S filesystem再次安装：
[root@cx-W55xEU /]# pacman -S filesystem
warning: filesystem-2015.09-1 is up to date -- reinstalling
resolving dependencies...
looking for conflicting packages...
Packages (1) filesystem-2015.09-1
Total Download Size: 0.01 MiB
Total Installed Size: 0.01 MiB
Net Upgrade Size: 0.00 MiB
:: Proceed with installation? [Y/n]
error: could not open file: /etc/mtab: No such file or directory
error: could not determine filesystem mount points
error: failed to commit transaction (unexpected error)
Errors occurred, no packages were upgraded.
我的/etc/mtab文件很干净，即没有内容
我发现了一个关于 arch wiki 的页面坐骑但不确定我是否应该创建指定的符号链接来解决此问题。
有什么建议么？