Свободное место на контроллере

Используйте команду df:

# df -hT
Filesystem     Type      Size  Used Avail Use% Mounted on
/dev/root      ext4      976M  633M  277M  70% /
devtmpfs       devtmpfs  240M     0  240M   0% /dev
tmpfs          tmpfs     248M     0  248M   0% /dev/shm
tmpfs          tmpfs     248M  520K  248M   1% /run
tmpfs          tmpfs     5.0M     0  5.0M   0% /run/lock
tmpfs          tmpfs     248M     0  248M   0% /sys/fs/cgroup
/dev/mmcblk0p6 ext4      4.7G  519M  4.0G  12% /mnt/data
tmpfs          tmpfs      50M     0   50M   0% /run/user/0

Можно также посмотреть, сколько места занимает каждый каталог:

# du -hd1 /
4.0K    /dev
555M    /var
6.5M    /sbin
5.3M    /etc
4.0K    /media
0       /sys
4.0K    /srv
583M    /usr
1.2M    /run
7.3M    /tmp
4.0K    /opt
7.2M    /bin
76M     /lib
47M     /home
du: cannot read directory '/mnt/sdcard': No such device
1.1G    /mnt
du: cannot access '/proc/6788/task/6788/fd/4': No such file or directory
du: cannot access '/proc/6788/task/6788/fdinfo/4': No such file or directory
du: cannot access '/proc/6788/fd/3': No such file or directory
du: cannot access '/proc/6788/fdinfo/3': No such file or directory
0       /proc
11M     /boot
16K     /root.default
2.4G    /