Linux Disk Usage
To display the amount of disk used in Linux in megabytes, you can use the df command with the -h option. This will display a list of all mounted filesystems on the system, along with the total size of the filesystem, the amount of space used, and the available space. The -h option stands for “human-readable”, and it causes the df command to display the sizes in a more readable format (e.g. “1G” for 1 gigabyte).
You can also use the –total option to display a grand total of all used and available space on all filesystems.
df -h --total