最近在阅读debian handbook的时候，发现debian系统，已经没有 /bin /sbin /lib目录，这3个目录是符号链接，指向/usr下面对应的目录。
yuanjp@debian:~$ ls / -l
total 68
lrwxrwxrwx 1 root root 7 Aug 14 07:34 bin -> usr/bin
drwxr-xr-x 4 root root 4096 Aug 14 08:49 boot
drwxr-xr-x 18 root root 3320 Aug 16 07:21 dev
drwxr-xr-x 124 root root 12288 Aug 16 07:22 etc
drwxr-xr-x 3 root root 4096 Aug 14 08:49 home
lrwxrwxrwx 1 root root 30 Aug 14 07:39 initrd.img -> boot/initrd.img-6.1.0-22-amd64
lrwxrwxrwx 1 root root 30 Aug 14 07:39 initrd.img.old -> boot/initrd.img-6.1.0-22-amd64
lrwxrwxrwx 1 root root 7 Aug 14 07:34 lib -> usr/lib
lrwxrwxrwx 1 root root 9 Aug 14 07:34 lib64 -> usr/lib64
drwx------ 2 root root 16384 Aug 14 07:32 lost+found
drwxr-xr-x 3 root root 4096 Aug 14 07:34 media
drwxr-xr-x 2 root root 4096 Aug 14 07:34 mnt
drwxr-xr-x 2 root root 4096 Aug 14 07:34 opt
dr-xr-xr-x 309 root root 0 Aug 16 07:21 proc
drwx------ 5 root root 4096 Aug 15 21:14 root
drwxr-xr-x 27 root root 700 Aug 16 07:22 run
lrwxrwxrwx 1 root root 8 Aug 14 07:34 sbin -> usr/sbin
drwxr-xr-x 2 root root 4096 Aug 14 07:34 srv
dr-xr-xr-x 13 root root 0 Aug 16 07:21 sys
drwxrwxrwt 17 root root 4096 Aug 16 07:26 tmp
drwxr-xr-x 12 root root 4096 Aug 14 07:34 usr
drwxr-xr-x 12 root root 4096 Aug 14 07:46 var
lrwxrwxrwx 1 root root 27 Aug 14 07:39 vmlinuz -> boot/vmlinuz-6.1.0-22-amd64
lrwxrwxrwx 1 root root 27 Aug 14 07:39 vmlinuz.old -> boot/vmlinuz-6.1.0-22-amd64
链接：
https://www.freedesktop.org/wiki/Software/systemd/TheCaseForTheUsrMerge/
这样做有很多好处，一个是为了和Unix系统兼容。