What is the benefit of the watch diff CLI command?

The watch diff command is a standard utility within the Arista EOS command-line interface (CLI). It is designed to enhance monitoring and troubleshooting by automatically re-executing a specified command at regular intervals. The diff keyword instructs the system to compare the output of the most recent command execution with the previous one and display only the lines that have changed. This is highly beneficial for observing dynamic changes in real-time, such as interface counter increments, routing protocol updates, or neighbor state fluctuations, without the clutter of unchanged information.

A. This describes a function related to big data analytics or scientific computing, not a network operating system CLI utility.

B. While you could use watch diff on an NTP status command, its primary benefit is general-purpose monitoring, not specifically calculating skew rates.

C. This is an overly specific application of a general utility; the command is not exclusively for PTP monitoring.

1. Arista Networks EOS User Manual, Release 4.21.0F, Section: "Command-Line Interface", Subsection: "Command Execution and Output Modification". This section details the watch command, explaining its syntax watch [] [diff] and its function to "execute a command repeatedly" with the diff option highlighting "the differences between successive updates."

2. Arista Networks, EOS Central, "EOS CLI Power Tools", Article: "Watching for changes". This official resource provides practical examples, stating, "The watch command can be used to repeatedly run a command... Adding the diff keyword will show only the differences between the last run and the current run of the command." It demonstrates usage with watch diff show ip route.