Cannabaceae

head
Developer(s)Various open-source and commercial developers
Operating systemUnix, Unix-like, MSX-DOS, IBM i
PlatformCross-platform
TypeCommand
Licensecoreutils: 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[edit]

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[edit]

-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 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.
-c ⟨bytes⟩
--bytes=⟨bytes⟩
Print first x number of bytes.

Other command[edit]

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[edit]

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[edit]

References[edit]

External links[edit]

One thought on “Cannabaceae

  1. Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
    View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction

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