我已经sudo do-release-upgrade从 16.04.3 LTS 执行，现在：
sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n]
Setting up keyboard-configuration (1.108ubuntu15.3) ...
/var/lib/dpkg/info/keyboard-configuration.postinst: line 103:
/etc/default/keyboard: Permission denied
dpkg: error processing package keyboard-configuration (--configure):
subprocess installed post-installation script returned error exit
status 1
Errors were encountered while processing:
keyboard-configuration
E: Sub-process /usr/bin/dpkg returned an error code (1)
我完全陷入困境，我该如何解决？
答案1
问题是/etc/default/keyboard无法写入。权限没问题
$ ls -l /etc/default/keyboard
-rw-r--r-- 1 root root 88 feb 27 23:05 /etc/default/keyboard
但文件属性错误：
$ lsattr /etc/default/keyboard
----i--------e-- /etc/default/keyboard
（i）属性方法不可变的。 也可以看看https://en.wikipedia.org/wiki/Chattr。
解决方案：
$ chattr -i /etc/default/keyboard
$ apt remove keyboard-configuration
$ apt install keyboard-configuration
$ apt upgrade