“df: cannot read table of mounted file systems”.

“df: cannot read table of mounted file systems”.
“df -l” returned an error: “df: cannot read table of mounted file systems”. I looked at my “/etc/mtab” file – empty! I did a “fdisk -l” and saw my partitions there, then proceeded to create a new mtab from my /proc/mount:
grep -v rootfs /proc/mounts > /etc/mtab

当出现以上错误时，只要运行一下以上命令即可。
grep -v rootfs /proc/mounts > /etc/mtab