谁能解释一下为什么？
# whoami
root
# ls -ld /usr/sbin
drwxr-xr-x 246 root wheel 8364 Jan 3 14:36 /usr/sbin
# pwd
/
# touch test-file
# ls -ltr test-file
-rw-r--r-- 1 root wheel 0 Jan 10 00:27 test-file
# cp test-file /usr/sbin
cp: /usr/sbin/test-file: Operation not permitted
# ls -ld@ /usr/sbin
drwxr-xr-x 246 root wheel 8364 Jan 3 14:36 /usr/sbin