I have Ubuntu 20.04. And I encounter this problem very often now -low disk space in "filesystem root" sometimes it shows 635MB available, sometimes 400MB. It seems that every time I work on Ubuntu or even when I use Google Chrome, the available disk space gets reduced.My laptop has a dual booting system with linux and windows. Currently my sda9 occupies a space of 25GB.
Please help!!

P.S. Someone had posted a similar question before but I couldn't get a satisfactory answer from that post, so please don't ignore this post.

Here is my output for `df -h`

```
Filesystem      Size  Used Avail Use% Mounted on
udev            3.8G     0  3.8G   0% /dev
tmpfs           784M  2.0M  782M   1% /run
/dev/sda9        25G   24G  124M 100% /
tmpfs           3.9G   17M  3.9G   1% /dev/shm
tmpfs           5.0M  4.0K  5.0M   1% /run/lock
tmpfs           3.9G     0  3.9G   0% /sys/fs/cgroup
/dev/loop0       98M   98M     0 100% /snap/core/10185
/dev/loop3       61M   61M     0 100% /snap/core20/634
/dev/loop1       98M   98M     0 100% /snap/core/10444
/dev/loop2       56M   56M     0 100% /snap/core18/1932
/dev/loop4       62M   62M     0 100% /snap/core20/875
/dev/loop5       56M   56M     0 100% /snap/core18/1885
/dev/loop6      163M  163M     0 100% /snap/gnome-3-28-1804/145
/dev/loop8       65M   65M     0 100% /snap/gtk-common-themes/1514
/dev/loop11     218M  218M     0 100% /snap/gnome-3-34-1804/60
/dev/loop10      50M   50M     0 100% /snap/snap-store/467
/dev/loop13      52M   52M     0 100% /snap/snap-store/498
/dev/loop15     180M  180M     0 100% /snap/telegram-desktop/2185
/dev/loop7       65M   65M     0 100% /snap/gtk-common-themes/1513
/dev/loop14     179M  179M     0 100% /snap/telegram-desktop/2198
/dev/loop12     261M  261M     0 100% /snap/kde-frameworks-5-core18/32
/dev/loop9      256M  256M     0 100% /snap/gnome-3-34-1804/36
/dev/sda1       746M   73M  674M  10% /boot/efi
tmpfs           784M   32K  784M   1% /run/user/1000

```