What utility would you use to check disk usage in Linux?

The utility used to check disk usage in Linux is actually "du." This command stands for "disk usage" and provides a way to estimate file space usage. It's particularly useful for identifying how much space individual directories and files are taking up.

On the other hand, "df" stands for "disk free" and is used to report the amount of available disk space on filesystems. While it provides overall information about free and used space on mounted filesystems, it does not show the usage of individual files or directories.

The utility "ls" is used to list files and directories within a directory and does not provide any information about disk usage. "diskus" is not a standard Linux command, making it a less viable option.

Thus, "du" is the appropriate tool for checking disk usage on a file or directory basis. Each of these utilities serves a specific purpose, making it important to choose the right one based on the information needed.