The head & tail command in Linux
head prints the first lines of a file and tail the last ones — ten by default. They are the natural tools for peeking at large files without loading them entirely, and tail in particular is a daily companion for anyone who works with servers, because tail -f follows a log file live as new lines are written to it.
How head & tail works
head is trivial: read from the start, stop after N lines — on a pipe or a file alike. tail on a regular file is cleverer: it seeks to the end and reads backwards until it has counted N newlines, so tailing the last lines of a multi-gigabyte log costs almost nothing. On a pipe, where seeking is impossible, tail must buffer as it reads — one of the few places the file-vs-stream distinction shows through.
Follow mode adds a loop: print the current end, then wait for the file to grow (via inotify on Linux, falling back to polling) and print the new bytes. The rotation trap lives here — plain -f follows the file descriptor, so when logrotate renames the file and creates a fresh one, -f keeps watching the old, now-renamed file in silence. -F follows the name, notices the swap and reopens. For anything long-running, -F is the correct spelling.
Syntax
head [-n N] FILE | tail [-n N] [-f] FILECommon options
| Option | What it does |
|---|---|
-n N | Print N lines instead of the default 10 (e.g. head -n 25 file). |
-c N | Print N bytes instead of lines. |
-f (tail) | Follow: keep the file open and print new lines as they are appended. Stop with Ctrl+C. |
-n +N (tail) | Start from line N to the end — tail -n +2 file skips a header line. |
How to use head & tail: examples
$ head server.logThe first 10 lines of the file.
$ head -n 3 data.csvJust the first 3 lines — perfect for checking a CSV header.
$ tail server.logThe last 10 lines — usually the most recent events in a log.
$ tail -n 100 app.log | grep ERRORSearch only the most recent part of a log.
$ tail -f /var/log/nginx/access.logWatch requests arrive in real time. The single most used debugging command on web servers.
$ tail -n +2 data.csvEverything except the first line — strip a CSV header before processing.
Real-world use cases for head & tail
Watching a deployment live
tail -f /var/log/app/deploy.log during a release shows each step as it happens; piped through grep --line-buffered ERROR it becomes a live failure detector. For anyone operating servers, tail -f is as fundamental as the prompt itself.
Sampling data files
A 10 GB CSV arrives. head -n 5 big.csv reveals the header and format instantly, without loading anything. head for the schema, tail for the freshest rows, wc -l for the size — the standard first contact with any large dataset.
Try head & tail yourself
This is a live sandbox with a small filesystem (documents/, notes.txt,
backup.sh…). Nothing you do here can break anything — experiment freely.
Try: head -n 2 notes.txt
Pro tips and common mistakes
- Prefer tail -F (capital) for logs: it survives log rotation by re-opening the file, where -f goes silent.
- Follow multiple logs at once: tail -f access.log error.log labels each chunk with its filename.
- Slice line ranges by combining: head -n 30 file | tail -n 11 prints lines 20–30.
- tail -n +2 data.csv skips the header row — the idiomatic prelude to piping a CSV into sort or awk.
Frequently asked questions about head & tail
What does tail -f do?
It prints the last lines of the file and then keeps waiting: every new line appended to the file appears immediately. It is the standard way to watch logs live. Press Ctrl+C to stop.
How do I see lines 20 to 30 of a file?
Combine both: head -n 30 file | tail -n 11 prints lines 20 through 30.
What is the difference between tail -n 5 and tail -n +5?
tail -n 5 prints the last five lines; tail -n +5 prints from line five to the end of the file.
Things people do with head & tail
Run Bash and executable scripts correctly using an interpreter, execute permissions and a shebang.
View the end of a fileUse tail to inspect recent log entries and control how many lines you see.
Watch a Linux log file in real timeFollow new log entries with tail and handle log rotation correctly.
Related commands
Print file contents, number lines, and join multiple files together.
grepFind lines matching a pattern in files or piped input — the workhorse of text search.