linux 为什么用du指令会出现部分无法读取的现象？
du -h --max-depth=1 /
113M /boot
0 /dev
du: cannot access ‘/proc/21419/task/21419/fd/4’: No such file or directory
du: cannot access ‘/proc/21419/task/21419/fdinfo/4’: No such file or directory
du: cannot access ‘/proc/21419/fd/3’: No such file or directory
du: cannot access ‘/proc/21419/fdinfo/3’: No such file or directory
0 /proc
12M /run
0 /sys
31M /etc
32K /root
207M /var
8.0K /tmp
1016M /usr
0 /home
0 /media
0 /mnt
0 /opt
0 /srv
1.4G /
