How can I know how much disk space I have in Linux or Unix?

df -h

df -h or du -h

df -h, df -k /some/dir if u want to check specific directory .

If I understand your question correctly, then you need to use this command line: df -h This will give you a summary of disks space, used space, available space, use percentage in human readable format.

df -h

du -k and df -k