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,
              Internationalization 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
              internationalization 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
              arguments and input files).

       LC_MESSAGES
              Determine the locale that should be used to  affect  the  format  and  contents  of
              diagnostic 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
       functionality.

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
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .