head command

head - output the first part of files

The head command in Linux is a simple utility used to display the beginning (top) of a file or input. It’s great for quickly checking the start of logs, scripts, or any text file without opening the whole thing.

Usage: head [OPTION]... [FILE]...

• OPTION: Flags which enhances the head abilities.
• FILE: The file(s) to read (optional; reads from input if omitted).

Print the first 10 lines of each FILE to standard output. With more than one FILE, precede each with a header giving the file name. With no FILE, or when FILE is -, read standard input.

Examples

• Basic Usage

  By default, head shows the first 10 lines of a file.

  $ head logfile.txt
  • Prints the first 10 lines of logfile.txt.
  • If the file has fewer than 10 lines, it shows the entire file.

• Specifying Number of Lines

  Use -n followed by a number to display a specific number of lines.

  $ head -n 5 logfile.txt
  • Shows the first 5 lines of logfile.txt.

  Shorthand:

  You can omit the -n and just use a dash with a number:

  head -5 logfile.txt
  • Same as above.

• Working with Multiple Files

  Pass multiple files to see the start of each one.

  $ head file1.txt file2.txt
  • Output includes the first 10 lines of file1.txt, then file2.txt, with a header like ==> file1.txt <== separating them.

  Single File with Multiple:

  To avoid headers for multiple files, use -q (quiet):

  $ head -q -n 5 file1.txt file2.txt
  • Shows 5 lines from each file without headers.

• Specifying Bytes Instead of Lines

  Use -c to display a specific number of bytes instead of lines.

  $ head -c 20 logfile.txt
  • Prints the first 20 bytes of logfile.txt (useful for binary files or precise cuts).

• Piping Input

  Use head with other commands via pipes to process output.

  $ ls -l | head -n 3
  • Shows the first 3 lines of the directory listing.

• Verbose Output for Multiple Files

  Add -v to always show file headers, even for a single file.

  head -v -n 5 logfile.txt
  • Output starts with ==> logfile.txt <== followed by the first 5 lines.

To get help related to the head command use --help option

$ head --help
Usage: head [OPTION]... [FILE]...
Print the first 10 lines of each FILE to standard output.
With more than one FILE, precede each with a header giving the file name.

With no FILE, or when FILE is -, read standard input.

Mandatory arguments to long options are mandatory for short options too.
  -c, --bytes=[-]NUM       print the first NUM bytes of each file;
                             with the leading '-', print all but the last
                             NUM bytes of each file
  -n, --lines=[-]NUM       print the first NUM lines instead of the first 10;
                             with the leading '-', print all but the last
                             NUM lines of each file
  -q, --quiet, --silent    never print headers giving file names
  -v, --verbose            always print headers giving file names
  -z, --zero-terminated    line delimiter is NUL, not newline
      --help     display this help and exit
      --version  output version information and exit

NUM may have a multiplier suffix:
b 512, kB 1000, K 1024, MB 1000*1000, M 1024*1024,
GB 1000*1000*1000, G 1024*1024*1024, and so on for T, P, E, Z, Y.
Binary prefixes can be used, too: KiB=K, MiB=M, and so on.