How can you test disk space availability in a Linux server?

To test disk space availability on a Linux server, utilizing the df command is highly effective. The df command stands for "disk free", and it provides a summary of available and used disk space on all mounted filesystems. When executed, it displays essential information such as the total size of each filesystem, the amount of space used, the amount of space available, and the percentage of disk space that is currently in use.

This command is particularly beneficial for administrators who need to monitor disk usage actively. It gives a holistic view of the filesystem's status, allowing for proactive management of disk space, which is critical for maintaining server health and performance.

The other options, while relating to file and system information, do not specifically address overall disk space availability in the same way. The ls command lists files within a directory but does not show details about total or available disk space. The du command reports the disk usage of files and directories, providing insights into space consumed by specific files rather than the overall availability across filesystems. Lastly, the free command gives information about memory usage (RAM), not disk usage, making it unrelated to the question of disk space availability.