head is a
program on
Unix
Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...
and
Unix-like
A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs.
Time-sharing operating systems scheduler (computing), schedule tasks for ef ...
s used to display the beginning of a text
file or
pipe
Pipe(s), PIPE(S) or piping may refer to:
Objects
* Pipe (fluid conveyance), a hollow cylinder following certain dimension rules
** Piping, the use of pipes in industry
* Smoking pipe
** Tobacco pipe
* Half-pipe and quarter pipe, semi-circul ...
d data.
Syntax
The command
syntax is:
head
ptions<file_name>
By default,
head
will print the first 10 lines of its input to the
standard output. The number of lines printed may be changed with a
command line
A command-line interpreter or command-line processor uses a command-line interface (CLI) to receive commands from a user in the form of lines of text. This provides a means of setting parameters for the environment, invoking executables and pro ...
option. The following example shows the first 20 lines of ''filename'':
head -n 20 ''filename''
This displays the first 5 lines of all files starting with ''foo'':
head -n 5 ''foo*''
Most versions allow omitting
n
and instead directly specifying the number:
-5
.
GNU head allows negative arguments for the
-n
option, meaning to print all but the last - argument value counted - lines of each input file.
Flags
-c
Copy first x number of bytes.
Other
Many early versions of Unix did not have this command, and documentation and books used sed instead:
sed 5q ''filename''
The example prints every line (implicit) and quit after the fifth.
Implementations
A head
command is also part of ASCII
ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because ...
's ''MSX-DOS2 Tools'' for MSX-DOS version 2. The command has also been ported to the IBM i
IBM i (the ''i'' standing for ''integrated'') is an operating system developed by IBM for IBM Power Systems. It was originally released in 1988 as OS/400, as the sole operating system of the IBM AS/400 line of systems. It was renamed to i5/OS i ...
operating system.
See also
* tail (Unix)
*dd (Unix)
dd is a command-line utility for Unix, Plan 9, Inferno, and Unix-like operating systems and beyond, the primary purpose of which is to convert and copy files. On Unix, device drivers for hardware (such as hard disk drives) and special device fi ...
*List of Unix commands
This is a list of Unix commands as specified by IEEE Std 1003.1-2008, which is part of the Single UNIX Specification (SUS). These commands can be found on Unix operating systems and most Unix-like operating systems.
List
See also
* List of G ...
References
External links
head
manual page from GNU coreutils
The GNU Core Utilities or coreutils is a package of GNU software containing implementations for many of the basic tools, such as cat, ls, and rm, which are used on Unix-like operating systems.
In September 2002, the ''GNU coreutils'' were c ...
.
FreeBSD documentation for head
{{Core Utilities commands
Unix text processing utilities
Unix SUS2008 utilities
IBM i Qshell commands