Tab 1: List of logins on Mar 13

Best Command:

grep "Mar 13" log.txt

Reasoning:

This command searches for lines in log.txt containing "Mar 13", which matches the date shown in the output. The result shows all login records for that day.

Tab 2: List of logins on Mar 12 (UPPERCASE) including REBOOT entries

Best Command:

awk '{ print toupper($0) }' log.txt

Reasoning:

All lines in the output are in UPPERCASE, including the word "REBOOT". This command converts every character in each line to uppercase, which matches the output format exactly.

Tab 3: List of unique usernames (sorted) including 'reboot'

Best Command:

awk '{ print $1 }' log.txt | sort | uniq

Reasoning:

This command extracts the first column (the username), sorts them, and removes duplicates, resulting in a list of unique usernames in alphabetical order. The output matches exactly.

 Tab 1 shows logins for "Mon Mar 13" –> grep "Mar 13" log.txt

 Tab 2 shows all entries in uppercase (including "REBOOT") for "Sun Mar 12" –> awk '{ print toupper($0) }' log.txt

 Tab 3 shows unique usernames in sorted order –> awk '{ print $1 }' log.txt | sort | uniq

 grep "Mar 13" log.txt

Searches for and displays all log entries from March 13.

 awk '{ print toupper($0) }' log.txt

Prints each line from log.txt in all uppercase letters (including system reboots).

 awk '{ print $1 }' log.txt | sort | uniq

Extracts just the username from each log entry, sorts them, and removes duplicates for a clean list.