Overview
The head command is a utility that displays the 'head', or beginning, of a file. By default, it outputs the first 10 lines, but users can specify the desired number of lines or bytes to control the output quantity. It is frequently used to check the format of log files or large data files, or to process the initial part of a file in scripts. While `head` handles the beginning of a file, `tail` handles the end of a file.
Key Features
Key features of the head command include:
- Outputs the beginning of text files.
- Outputs the first 10 lines by default.
- Allows specifying the number of lines (-n) or bytes (-c) to output.
- Can take multiple files as arguments and output their content, separated by file.
Key Options
Commonly used head command options are grouped by purpose.
1) Output Options
2) Help
Generated command:
Try combining the commands.
Description:
`head` Executes the command.
Combine the above options to virtually execute commands with AI.
Usage Examples
Explore the various usage examples of the head command to learn its functionalities.
Output First 10 Lines (Default)
head /etc/passwdOutputs the first 10 lines of the `/etc/passwd` file.
Output First 5 Lines
head -n 5 file.txtUses the `-n` option to output the first 5 lines of `file.txt`.
Output First 50 Bytes
head -c 50 log.txtUses the `-c` option to output the first 50 bytes of the `log.txt` file.
Usage with Pipe (|)
ls -l | head -n 5Checks only the first 5 lines of the `ls -l` command's output.
Output First 3 Lines of Multiple Files
head -n 3 file1.txt file2.txtOutputs the first 3 lines of file1.txt and file2.txt respectively. File name headers are also displayed.
Tips & Cautions
Points to note when using the head command are summarized here.
Tips
- `head` can be used with `tail` to perform more complex tasks, such as outputting the middle part of a file. For example, `head -n 20 file.txt | tail -n 10` outputs lines 11 through 20.
- When specifying the number of lines or bytes, simply typing a number after a hyphen, like `head -5 file.txt`, is considered the `-n` option.
- When dealing with large files, using `head` is very efficient as it does not load the entire file into memory.