为什么在Ubuntu 20.04中现在/ bin和/ sbin现在是符号链接?

tl; dr:在Ubuntu 20.04中,/ bin和/ sbin等文件夹现在是/ usr中相同文件夹的符号链接。为什么要进行此更改,发行说明中是否应该提及此更改?

This took a few days, but I tracked down some issues I was having in system setup. As part of a preseed post-install set of commands, I unpack a .tar.gz onto new systems, which puts some files in various folders, including /bin. I've been doing this since Ubuntu 14.04. With Ubuntu 20.04, my systems weren't bootable after install (various failure to mount errors).

最后,我将问题缩小到解压缩步骤,并意识到我正在替换/ bin文件夹并使许多内容无法访问。真是个惊喜。修复很容易;转储文件在/ usr / bin中。

具体来说,以下符号链接显然是20.04中的新增功能:

$ lsb_release -ds
Ubuntu 20.04 LTS
$ ls -l / | grep -E "usr|bin|lib"
lrwxrwxrwx   1 root root     7 Apr 23 15:02 bin -> usr/bin/
lrwxrwxrwx   1 root root     7 Apr 23 15:02 lib -> usr/lib/
lrwxrwxrwx   1 root root     8 Apr 23 15:02 sbin -> usr/sbin/
drwxr-xr-x  11 root root  4096 Apr 23 15:05 usr/

与19.10比较:

$ lsb_release -ds
Ubuntu 19.10
$ ls -l / | grep -E "usr|bin|lib"
drwxr-xr-x   2 root root  4096 Dec 11 07:41 bin
drwxr-xr-x  20 root root  4096 Nov  4  2019 lib
drwxr-xr-x   2 root root  4096 Nov  3  2019 lib64
drwxr-xr-x   2 root root 12288 Apr  6 13:29 sbin
drwxr-xr-x  11 root root  4096 Aug  5  2019 usr

Arch does this, apparently starting years ago, and the overall topic is the Filesystem Hierachy Standard . It's not in the release notes: https://wiki.ubuntu.com/FocalFossa/ReleaseNotes