How to use tail and head for log analysis

Short answer

head shows the start of a file; tail shows the end and can follow files in real time.

Steps

1. View first 10 lines:

head file.txt

2. View last 20 lines:

tail -n 20 file.txt

3. Follow a log in real time:

tail -f /var/log/syslog

4. Combine:

cat file.txt | head -50 | tail -10

Tips

• tail -F follows across log rotations.
• Use grep piped into tail to filter then view recent matches.
• head and tail work on piped input, not just files.

Common issues

• tail -f stops when the file is truncated; use -F for robust following.
• Binary files may produce garbled output.