I build my embeded linux system use busybox and has a /etc/fstab file: none /tmp tmpfs defaults,noatime,nosuid,nodev,mode=1777,size=64M 0 0 none /run tmpfs defaults,noatime,nosuid,nodev,mode=1777,size=4M 0 0 none /proc proc defaults 0 0 udev /dev devtmpfs defaults 0 0 none /dev/pts devpts defaults 0 0 none /sys sysfs defaults 0 0 nodev /sys/kernel/debug debugfs defaults 0 0 but mount /dev/pts will failed, because no directory /dev/pts. When I 'man mount', I found a mount option X-mount.mkdir but it seems not supported by busybox.