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Linux 2.6 - man page for cut (linux section 1posix)

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

NAME
       cut - cut out selected fields of each line of a file

SYNOPSIS
       cut -b list [-n] [file ...]

       cut -c list [file ...]

       cut -f list [-d delim][-s][file ...]

DESCRIPTION
       The  cut  utility shall cut out bytes ( -b option), characters ( -c option), or character-
       delimited fields ( -f option) from each line in one or more files, concatenate  them,  and
       write them to standard output.

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

       The application shall ensure that the option-argument list (see options	-b,  -c,  and  -f
       below) is a comma-separated list or <blank>-separated list of positive numbers and ranges.
       Ranges can be in three forms. The first is two positive numbers separated by  a	hyphen	(
       low-  high),  which  represents all fields from the first number to the second number. The
       second is a positive number preceded by a hyphen (- high),  which  represents  all  fields
       from  field number 1 to that number. The third is a positive number followed by a hyphen (
       low-), which represents that number to the last field, inclusive. The elements in list can
       be repeated, can overlap, and can be specified in any order, but the bytes, characters, or
       fields selected shall be written in the order of the input data.  If an element appears in
       the selection list more than once, it shall be written exactly once.

       The following options shall be supported:

       -b  list
	      Cut  based  on  a  list  of bytes. Each selected byte shall be output unless the -n
	      option is also specified. It shall not be an error to select bytes not  present  in
	      the input line.

       -c  list
	      Cut  based  on  a  list  of characters. Each selected character shall be output. It
	      shall not be an error to select characters not present in the input line.

       -d  delim
	      Set the field delimiter to the character delim. The default is the <tab>.

       -f  list
	      Cut based on a list of fields, assumed to be separated in the file by  a	delimiter
	      character  (see  -d).  Each  selected field shall be output. Output fields shall be
	      separated by a single occurrence of the field delimiter character.  Lines  with  no
	      field  delimiters  shall be passed through intact, unless -s is specified. It shall
	      not be an error to select fields not present in the input line.

       -n     Do not split characters. When specified with the -b option, each element in list of
	      the form low- high (hyphen-separated numbers) shall be modified as follows:

	       * If  the  byte selected by low is not the first byte of a character, low shall be
		 decremented to select the first byte of the  character  originally  selected  by
		 low.  If  the	byte  selected	by high is not the last byte of a character, high
		 shall be decremented to select the last byte of the character prior to the char-
		 acter	originally  selected  by high, or zero if there is no prior character. If
		 the resulting range element has high equal to zero or low greater than high, the
		 list  element	shall be dropped from list for that input line without causing an
		 error.

       Each element in list of the form low- shall be treated as above with high set to the  num-
       ber of bytes in the current line, not including the terminating <newline>. Each element in
       list of the form - high shall be treated as above with low set to 1. Each element in  list
       of  the	form num (a single number) shall be treated as above with low set to num and high
       set to num.

       -s     Suppress lines with no delimiter characters, when used with the -f  option.  Unless
	      specified, lines with no delimiters shall be passed through untouched.

OPERANDS
       The following operand shall be supported:

       file   A  pathname of an input file. If no file operands are specified, or if a file oper-
	      and is '-' , the standard input shall be used.

STDIN
       The standard input shall be used only if no file operands are specified, or if a file  op-
       erand is '-' .  See the INPUT FILES section.

INPUT FILES
       The input files shall be text files, except that line lengths shall be unlimited.

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

       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 cut utility output shall be a concatenation of  the	selected  bytes,  characters,  or
       fields (one of the following):

	      "%s\n", <concatenation of bytes>

	      "%s\n", <concatenation of characters>

	      "%s\n", <concatenation of fields and field delimiters>

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     All input files were output successfully.

       >0     An error occurred.

CONSEQUENCES OF ERRORS
       Default.

       The following sections are informative.

APPLICATION USAGE
       Earlier	versions  of  the cut utility worked in an environment where bytes and characters
       were considered equivalent (modulo <backspace> and <tab> processing  in	some  implementa-
       tions).	In the extended world of multi-byte characters, the new -b option has been added.
       The -n option (used with -b) allows it to be used to act on  bytes  rounded  to	character
       boundaries. The algorithm specified for -n guarantees that:

	      cut -b 1-500 -n file > file1
	      cut -b 501- -n file > file2

       ends  up  with all the characters in file appearing exactly once in file1 or file2. (There
       is, however, a <newline> in both file1 and file2 for each <newline> in file.)

EXAMPLES
       Examples of the option qualifier list:

       1,4,7  Select the first, fourth, and seventh bytes, characters, or fields and field delim-
	      iters.

       1-3,8  Equivalent to 1,2,3,8.

       -5,10  Equivalent to 1,2,3,4,5,10.

       3-     Equivalent to third to last, inclusive.

       The  low-  high	forms  are  not always equivalent when used with -b and -n and multi-byte
       characters; see the description of -n.

       The following command:

	      cut -d : -f 1,6 /etc/passwd

       reads the System V password file (user database) and produces lines of the form:

	      <user ID>:<home directory>

       Most utilities in this volume of IEEE Std 1003.1-2001 work on text files. The cut  utility
       can  be used to turn files with arbitrary line lengths into a set of text files containing
       the same data. The paste utility can be used to create (or recreate) files with	arbitrary
       line lengths. For example, if file contains long lines:

	      cut -b 1-500 -n file > file1
	      cut -b 501- -n file > file2

       creates	file1  (a text file) with lines no longer than 500 bytes (plus the <newline>) and
       file2 that contains the remainder of the data from file. (Note that file2 is  not  a  text
       file if there are lines in file that are longer than 500 + {LINE_MAX} bytes.) The original
       file can be recreated from file1 and file2 using the command:

	      paste -d "\0" file1 file2 > file

RATIONALE
       Some historical implementations do not count <backspace>s in determining character  counts
       with  the -c option. This may be useful for using cut for processing nroff output.  It was
       deliberately decided not to have the -c option treat either <backspace>s or <tab>s in  any
       special fashion. The fold utility does treat these characters specially.

       Unlike  other  utilities, some historical implementations of cut exit after not finding an
       input file, rather than continuing to process the remaining file operands.  This  behavior
       is  prohibited  by  this  volume  of  IEEE Std 1003.1-2001,  where only the exit status is
       affected by this problem.

       The behavior of cut when provided with either mutually-exclusive options or  options  that
       do  not	work logically together has been deliberately left unspecified in favor of global
       wording in Utility Description Defaults .

       The OPTIONS section was changed in response to IEEE PASC Interpretation 1003.2  #149.  The
       change  represents  historical  practice  on  all known systems. The original standard was
       ambiguous on the nature of the output.

       The list option-arguments are historically used to select the portions of the line  to  be
       written, but do not affect the order of the data. For example:

	      echo abcdefghi | cut -c6,2,4-7,1

       yields "abdefg" .

       A proposal to enhance cut with the following option:

       -o     Preserve	the selected field order. When this option is specified, each byte, char-
	      acter, or field (or ranges of such) shall be written in the order specified by  the
	      list  option-argument,  even  if	this requires multiple outputs of the same bytes,
	      characters, or fields.

       was rejected because this type of enhancement is outside the scope  of  the  IEEE P1003.2b
       draft standard.

FUTURE DIRECTIONS
       None.

SEE ALSO
       grep , paste , Parameters and Variables

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					   CUT(P)


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