Head (Unix)

{{Infobox software | name = head | logo = | screenshot = Head-example-command.gif | screenshot size = | caption = Example usage of <code>head</code> command to display first 5 lines of Lorem ipsum in the specified file | author = | developer = Various open-source and commercial developers | released = | latest release version = | latest release date = | operating system = Unix, Unix-like, MSX-DOS, IBM i | platform = Cross-platform | genre = Command | license = coreutils: GPLv3 | website = }}

'''{{code|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] {{angbr|file_name}}

By default, {{tt|head}} will print the first 10 lines of its input to the standard output.

===Option flags===

{{glossary}} {{term|1=-n|2={{tt|-n}} {{angbr|count}}}} {{term|1=--lines|2={{tt|--lines}}={{angbr|count}}}} {{defn|1= The number of lines printed may be changed with a command line option. The following example shows the first 20 lines of ''filename'':

This displays the first 5 lines of all files starting with ''foo'':

Most versions{{citation needed|date=June 2020}} allow omitting <code>n</code> and instead directly specifying the number: <code>-5</code>. GNU head allows negative arguments for the <code>-n</code> option, meaning to print all but the last - argument value counted - lines of each input file. }} {{term|1=-c|2={{tt|-c}} {{angbr|bytes}}}} {{term|1=--bytes|2={{tt|--bytes}}={{angbr|bytes}}}} {{defn|Print first x number of bytes.}} {{glossary end}}

==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.<ref>{{cite journal |last1=Spinellis |first1=Diomidis |title=dspinellis/unix-history-man: Version 1.0 web pages (v1.1-web) |journal=Zenodo |date=2022 |doi=10.5281/zenodo.7248228 |url=https://dspinellis.github.io/unix-history-man/man1.html}}</ref>

==Implementations== A <code>head</code> command is also part of ASCII's ''MSX-DOS2 Tools'' for MSX-DOS version 2.<ref>[https://archive.org/details/MSXDOS2TOOLS MSX-DOS2 Tools User's Manual by ASCII Corporation]</ref> The {{Mono|head}} command has also been ported to the IBM i operating system.<ref>{{cite web |title=IBM System i Version 7.2 Programming Qshell |language=en |author=IBM |author-link=IBM |url=https://www.ibm.com/support/knowledgecenter/ssw_ibm_i_74/rzahz/rzahzpdf.pdf?view=kc |access-date=2020-09-05 |archive-date=2020-09-18 |archive-url=https://web.archive.org/web/20200918130823/https://www.ibm.com/support/knowledgecenter/ssw_ibm_i_74/rzahz/rzahzpdf.pdf?view=kc |url-status=live }}</ref>

==See also== *tail (Unix) *dd (Unix) *List of Unix commands

==References== {{Reflist}}

==External links== {{Wikibooks|Guide to Unix|Commands}} *[https://www.gnu.org/software/coreutils/manual/html_node/head-invocation.html head] manual page from GNU coreutils. *[http://www.freebsd.org/cgi/man.cgi?query=head&apropos=0&sektion=0&manpath=FreeBSD+5.3-RELEASE+and+Ports&format=html FreeBSD documentation for head]

Category:Unix text processing utilities Category:Unix SUS2008 utilities Category:IBM i Qshell commands