What command shows device log usage for all logging devices?

The command that shows device log usage for all logging devices is "Diagnose log device." This command is specifically designed to provide insights into the log usage statistics of connected logging devices. By using this command, administrators can effectively monitor the overall logging status, including the number of logs being generated by each device and the available space, which is crucial for maintaining optimal logging performance and ensuring that logs are retained according to organizational policies.

In contrast, the other commands serve different purposes. For example, the "Diagnose fortilogd lograte" command focuses on the log rate specifically related to the FortiLog daemon, which is not comprehensive for all logging devices. Meanwhile, "Di de en" appears to be truncated and does not correspond to a recognized command in the context of log usage. Lastly, "Diagnose sql status sqlplugind" pertains to the status of the SQL plugin, which is unrelated to general log usage metrics. Therefore, understanding the specific functionalities of these commands clarifies why "Diagnose log device" is the appropriate choice for viewing device log usage.