Which of the following commands is best for monitoring real-time log file updates?

• A. tail -F
• B. head
• C. grep
• D. cat

Answer: (A)

The command tail -F is ideal for monitoring real-time log file updates because it outputs the last part of a file and continues to display new lines as they are added. This is particularly useful for system administrators and developers who need to watch logs for real-time updates, such as those generated by web servers or applications. The usage of -F allows it to follow the file even if it gets rotated (i.e., renamed and a new file created in its place), making it superior to simply using tail -f, which can break if the file is replaced during logging.

Other commands do not provide the same functionality. For example, head displays the first part of a file and is not designed for ongoing monitoring. grep is a powerful command for searching through files for specific patterns but does not inherently monitor changes over time. Similarly, cat will output the entire contents of a file at once but does not keep track of updates as they occur. Therefore, tail -F stands out as the best choice for watching log files in real-time.