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HEAD(P) 			    POSIX Programmer's Manual				  HEAD(P)

NAME
       head - copy the first part of files

SYNOPSIS
       head [-n number][file...]

DESCRIPTION
       The  head utility shall copy its input files to the standard output, ending the output for
       each file at a designated point.

       Copying shall end at the point in each input file indicated by the -n number  option.  The
       option-argument number shall be counted in units of lines.

OPTIONS
       The  head  utility  shall  conform to the Base Definitions volume of IEEE Std 1003.1-2001,
       Section 12.2, Utility Syntax Guidelines.

       The following option shall be supported:

       -n  number
	      The first number lines of each input file shall be copied to standard  output.  The
	      application  shall  ensure  that	the  number option-argument is a positive decimal
	      integer.

       When a file contains less than number lines, it shall be copied to standard output in  its
       entirety. This shall not be an error.

       If no options are specified, head shall act as if -n 10 had been specified.

OPERANDS
       The following operand shall be supported:

       file   A  pathname of an input file. If no file operands are specified, the standard input
	      shall be used.

STDIN
       The standard input shall be used only if no file operands are  specified.  See  the  INPUT
       FILES section.

INPUT FILES
       Input  files  shall  be	text  files,  but the line length is not restricted to {LINE_MAX}
       bytes.

ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of head:

       LANG   Provide a default value for the internationalization variables that  are	unset  or
	      null. (See the Base Definitions volume of IEEE Std 1003.1-2001, Section 8.2, Inter-
	      nationalization Variables for the precedence of internationalization variables used
	      to determine the values of locale categories.)

       LC_ALL If  set  to a non-empty string value, override the values of all the other interna-
	      tionalization variables.

       LC_CTYPE
	      Determine the locale for the interpretation of sequences of bytes of text  data  as
	      characters  (for	example, single-byte as opposed to multi-byte characters in argu-
	      ments and input files).

       LC_MESSAGES
	      Determine the locale that should be used to affect the format and contents of diag-
	      nostic messages written to standard error.

       NLSPATH
	      Determine the location of message catalogs for the processing of LC_MESSAGES .

ASYNCHRONOUS EVENTS
       Default.

STDOUT
       The standard output shall contain designated portions of the input files.

       If  multiple  file operands are specified, head shall precede the output for each with the
       header:

	      "\n==> %s <==\n", <pathname>

       except that the first header written shall not include the initial <newline>.

STDERR
       The standard error shall be used only for diagnostic messages.

OUTPUT FILES
       None.

EXTENDED DESCRIPTION
       None.

EXIT STATUS
       The following exit values shall be returned:

	0     Successful completion.

       >0     An error occurred.

CONSEQUENCES OF ERRORS
       Default.

       The following sections are informative.

APPLICATION USAGE
       The obsolescent - number form is withdrawn in this version.  Applications should  use  the
       -n number option.

EXAMPLES
       To  write  the  first  ten  lines of all files (except those with a leading period) in the
       directory:

	      head *

RATIONALE
       Although it is possible to simulate head with sed 10q for  a  single  file,  the  standard
       developers  decided  that  the  popularity of head on historical BSD systems warranted its
       inclusion alongside tail.

       This standard version of head follows the Utility Syntax Guidelines.  The  -n  option  was
       added to this new interface so that head and tail would be more logically related.

       There  is  no  -c  option  (as there is in tail) because it is not historical practice and
       because other utilities in this volume of IEEE Std 1003.1-2001 provide similar functional-
       ity.

FUTURE DIRECTIONS
       None.

SEE ALSO
       sed , tail

COPYRIGHT
       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information Technology  --  Portable	Operating  System
       Interface  (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
       the Institute of Electrical and Electronics Engineers, Inc and  The  Open  Group.  In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group Standard is the referee document. The orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003					  HEAD(P)
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