Which command displays the current disk space usage for all mounted file systems?

 The command df displays the current disk space usage for all mounted file systems. It shows the size, used space, available space, percentage of usage, and mount point of each file system. By default, the output is in 1K blocks, but it can be changed with options like -h (human-readable), -B (block size), -i (inodes), and -T (type). The command df is part of the 101.1 Determine and configure hardware settings topic of the LPI Linux Essentials certification program12. References:

Linux Essentials - Linux Professional Institute Certification Programs1

Exam 101 Objectives - Linux Professional Institute