Viewing Files with cat, less, head, and tail

You do not need an editor simply to inspect text. cat, less, head, and tail all read files, but suit different lengths and positions.

cat: quickly print a short file

cat settings.conf prints everything at once, which is convenient for a short file. A long file scrolls past quickly and is better suited to less. cat part1.txt part2.txt prints both files in order, reflecting the original meaning of concatenate.

less: page and search

less system.log opens a scrollable pager. Arrow keys, Page Up, Page Down, or space commonly navigate; q exits, and /error searches for error. Exact shortcuts vary, but paging and search are the essentials.

cat short file, all content

less long file, page and search

head beginning only

tail end only

tail -f follow new lines

head and tail: choose one end

head access.log normally shows the first 10 lines, useful for a CSV header or configuration opening. head -n 20 access.log requests 20. tail normally shows the last 10 lines, where the newest log entries usually appear; tail -n 20 requests 20.

tail -f: continuously follow a log

tail -f app.log keeps running and shows lines as they are appended. It is common during server troubleshooting. The shell prompt does not return immediately; press Ctrl+C to stop it.

short → cat*·long → less·start → head·end → tail·*new → tail -f

Selection questions: How long is the file? Which part do you need? Is it still growing? Those answers usually identify the right command.

Simulated terminal ready. Run commands and watch the filesystem on the right.