Install the quota tools on your server.(debian – ubuntu)

sudo apt install quota

Edit your fstab file under etc folder:

/dev/sda1 / ext4 usrquota,grpquota 0 0

and remount it to take effect immediately:

sudo mount -o remount / (or whereever you want to enable)

Enable quota.This command will create two files on file system like /aquota.user and /aquota.group :

sudo quotacheck -ugm /

Activate the quota

sudo quotaon -v /