Head (Unix)
Example usage of head command to display first 5 lines of Lorem ipsum in the specified file | |
Developer(s) | Various open-source and commercial developers |
---|---|
Operating system | Unix, Unix-like, MSX-DOS, IBM i |
Platform | Cross-platform |
Type | Command |
License | coreutils: GPLv3 |
head is a program on Unix and Unix-like operating systems used to display the beginning of a text file or piped data.
Syntax
The command syntax is:
head [options] ⟨file_name⟩
By default, head will print the first 10 lines of its input to the standard output.
Option flags
- -n ⟨count⟩
- --lines=⟨count⟩
- The number of lines printed may be changed with a command line 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[citation needed] allow omittingn
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. - -c ⟨bytes⟩
- --bytes=⟨bytes⟩
- Print first x number of bytes.
Other command
Many early versions of Unix and Plan 9 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.
Equivalently, awk may be used to print the first five lines in a file:
awk 'NR < 6' filename
However, neither sed nor awk were available in early versions of BSD, which were based on Version 6 Unix, and included head.[1]
Implementations
A head
command is also part of ASCII's MSX-DOS2 Tools for MSX-DOS version 2.[2] The head command has also been ported to the IBM i operating system.[3]
See also
- tail (Unix)
- dd (Unix)
- List of Unix commands
References
External links
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