The head command in Linux is a simple but powerful utility used to display the beginning portion of files. By default, it outputs the first 10 lines of a file, though this number can be easily customized. This command is particularly useful when you want to quickly preview the contents of large files, check file headers, or view the beginning of log files without opening the entire document.
Display the First 10 Lines of a File
head file.txt
Shows the default first 10 lines of file.txt.
Show a Specific Number of Lines
head -n 5 file.txt
Displays the first 5 lines of file.txt.
View the Beginning of Multiple Files
head file1.txt file2.log
Shows the first 10 lines of both files, with headers indicating each file name.
Display Bytes Instead of Lines
head -c 100 file.txt
Outputs the first 100 bytes of the file (useful for binary or fixed-size data).
Combine with tail to Extract a Middle Section
head -20 file.txt | tail -10- Gets lines 11–20 of
file.txt(first 20 lines viahead, then last 10 viatail).
Suppress File Headers in Output
head -q file1.txt file2.txt
Hides filenames when viewing multiple files (-q = quiet mode).
Always Show Filename Headers
head -v file.txt
Forces the filename header, even for a single file (-v = verbose).
Pipe Output from Another Command
ls -l /var/log | head -n 3
Lists files in /var/log and shows the first 3 entries.
Redirect Output to a New File
head -n 5 file.txt > top_lines.txt
Saves the first 5 lines of file.txt into top_lines.txt.
Monitor Real-Time Logs (Partial Preview)
tail -f access.log | head -n 20
Note: This isn’t truly real-time but captures the first 20 lines of the streaming log.
Key Notes:
- Default Behavior:
headshows the first 10 lines if no options are specified. - Large Files: Safe for massive files (e.g., logs) since it doesn’t load the entire file.
- Binary Files: Use
-cto preview bytes, but avoid text operations on binaries.
