Which command line tool should a technician use to inspect free disk space on the /dev/sda partition in a Linux server?

The command line tool that a technician should use to inspect free disk space on the /dev/sda partition in a Linux server is the tool designed specifically for this purpose: the 'df' command. This command stands for "disk filesystem" and displays the amount of disk space used and available on file systems. When you execute 'df', it reports the total size, used space, available space, and the mount points of the specified partitions, making it an ideal choice for checking disk space.

In contrast, the other tools serve different functions. The 'dd' command is primarily used for low-level copying and converting of raw data, which does not provide disk usage information. The 'du' command estimates file space usage, which is more about how much space files and directories consume rather than the overall free space on a filesystem. The 'ls' command lists directory contents, providing details about files and directories but not related to the overall disk space or partition availability.