CompTIA Linux+ XK0-006 (V8) Practice Question

The task requires a command that meets several criteria:

• Recursive search: This is provided by the -r or -R option.
• Show line numbers: The -n option adds line numbers to the output.
• Display the filename: When performing a recursive search, grep automatically prefixes each match with the file path; no extra option is needed.
• Suppress error messages: The -s (or --no-messages) option suppresses errors for unreadable files.

The only answer that combines all the necessary options is grep -Rns "PermitRootLogin" /etc. The options -R, -n, and -s can be combined as -Rns (or -rns).

Why the distractors are wrong:

• grep -rql "PermitRootLogin" /etc uses -q (quiet) and -l (list files), which prevents it from printing the matching lines and their line numbers.
• grep -Rin "PermitRootLogin" /etc is missing the -s option, so it will still display "Permission denied" errors.
• grep -r "PermitRootLogin" /etc 2>/dev/null successfully suppresses error messages by redirecting stderr, but it lacks the -n option to display line numbers.