# Cheatsheet & Examples: head

The `head` command displays the beginning of a file, typically the first 10 lines by default. It is useful for quickly previewing files without opening them entirely.

## Display the first 10 lines of a file  
Example Usage:  
`head filename.txt`  

What it does:  
Prints the first 10 lines of the specified file.  

Command-line Arguments Explained:  
- `filename.txt`: The file whose content is to be displayed.  

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## Display a specified number of lines  
Example Usage:  
`head -n 5 filename.txt`  

What it does:  
Prints the first 5 lines of the file.  

Command-line Arguments Explained:  
- `-n 5`: Specifies the number of lines to display (in this case, 5).  
- `filename.txt`: The file to be read.  

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## Display a specified number of bytes  
Example Usage:  
`head -c 100 filename.txt`  

What it does:  
Prints the first 100 bytes of the file.  

Command-line Arguments Explained:  
- `-c 100`: Specifies the number of bytes to display (in this case, 100).  
- `filename.txt`: The file to be read.  

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## Suppress headers when viewing multiple files  
Example Usage:  
`head -q -n 3 file1.txt file2.txt`  

What it does:  
Displays the first 3 lines of each file without printing filenames as headers.  

Command-line Arguments Explained:  
- `-q`: Suppresses the display of filenames for multiple files.  
- `-n 3`: Specifies the number of lines to display (3 in this case).  

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## Display the first 10 lines of standard input  
Example Usage:  
`head`  

What it does:  
Reads and displays the first 10 lines of input from the standard input stream (e.g., user input or piped data).  

Command-line Arguments Explained:  
- No arguments: Uses default behavior (first 10 lines).  

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## Display the first 10 lines of multiple files  
Example Usage:  
`head file1.txt file2.txt`  

What it does:  
Prints the first 10 lines of each specified file, including their filenames as headers.  

Command-line Arguments Explained:  
- `file1.txt`: The first file to be read.  
- `file2.txt`: The second file to be read.  

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## Display the first 5 lines of a file and write to another file  
Example Usage:  
`head -n 5 filename.txt > output.txt`  

What it does:  
Extracts the first 5 lines of `filename.txt` and saves them to `output.txt`.  

Command-line Arguments Explained:  
- `-n 5`: Specifies the number of lines to display (5 in this case).  
- `filename.txt`: The source file.  
- `> output.txt`: Redirects the output to a new file.  

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## Follow a file's content in real time  
Example Usage:  
`head -f log.txt`  

What it does:  
Continuously displays new lines added to `log.txt` as they are written, useful for monitoring logs.  

Command-line Arguments Explained:  
- `-f`: Enables "follow" mode, keeping the command running to show updates.  
- `log.txt`: The file to monitor for new content.  

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## Display the first 10 lines of a file with verbose output  
Example Usage:  
`head -v filename.txt`  

What it does:  
Prints the first 10 lines of the file, along with the filename as a header (even for a single file).  

Command-line Arguments Explained:  
- `-v`: Enables verbose mode, showing filenames for individual files.  
- `filename.txt`: The file to be read.