cat Options

cat has a couple of handy options that make reading files easier.

Numbering lines: cat -n

The -n option puts a line number in front of every line:

cat -n crew.txt

     1	Ava
     2	Ben
     3	Chloe

This is great when you need to refer to "line 12" of a file, or count how far down something is.

Joining files

You already know cat can print several files in a row. That is its real super-power, concatenating them:

cat header.txt body.txt footer.txt

The three files are printed one after another, top to bottom, as if they were a single document. Combine this with numbering:

cat -n part1.txt part2.txt

The numbering runs continuously across both files.

(In a later chapter you will learn how to save this joined output into a new file using redirection. For now, just enjoy seeing it on screen.)

Mission: Assemble and Archive the Crew Roster

The station's crew list got split into two files: team-a.txt and team-b.txt. Command needs a combined view, a numbered roll call, and both files kept together for the record.

1. Print team-a.txt and team-b.txt together in one go.
2. Print both files again, this time with a line number in front of every line, running continuously across both.
3. Create a folder called roster and copy both team files into it.
4. Confirm the archive by printing roster/team-a.txt with its lines numbered.

Expected result

Both teams appear one after another, then the same names with continuous line numbers. The roster folder holds a copy of each team file.