How to see free space on unix system.

[oracle@itc-799 ~]$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 100G 72G 24G 76% /
/dev/sda2 341G 205G 119G 64% /data
/dev/sda1 92M 12M 76M 14% /boot
tmpfs 2.0G 0 2.0G 0% /dev/shm

df -h is command to check space usage on unix system, type this command on unix prompt and the out will be like above detail. In the above example, we have two mount points “/” and “/data” which we can use. In local environment usually we have two or one mount point.

Let’s talk about these mount points one by one.
/dev/sda3 100G 72G 24G 76% /

This mount point is known as root mount point and has total 100G of space out of which 72G is used and 24G is available.

/dev/sda2 341G 205G 119G 64% /data

This mount point is known as data mount point as given name and have 341G of space out of which 205G is used and 119G is free and the used percentage is 64%.

Some systems may have more mount points like

Filesystem Size Used Avail Use% Mounted on
/dev/sda3 100G 72G 24G 76% /
/dev/sda2 341G 205G 119G 64% /data
/dev/sda4 341G 205G 119G 64% /data1
/dev/sda1 92M 12M 76M 14% /boot
tmpfs 2.0G 0 2.0G 0% /dev/shm

This system has there mount points “/” , “/data” and “/data1”.