Command for cumulative disk space

Linux and Unix-Like Red Hat
1

I wanted to know the Red Hat Linux command for cumulative disk space usage and the free space as df -h gives used and free space individually for the drives. Or, a command to check free space on the server would also be fine.

I hope, my question is clear.

Please revert with the reply to my query.

Regards

2

There's got to be a neat way of summing a column which meets given criteria using awk only, which someone will no doubt enlighten me with.

In the interim, this works under bash and ensures that the tempfs isn't counted as real space

total_free=0;for i in $(df -k | egrep '^/dev'| awk '{print $4}' ) ; do total_free=$(($total_free + $i)); done ; echo Total free space on $(hostname) is ${total_free}K
3

Thanks for your answer.