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OpenDarwin 7.2.1 - man page for sort (opendarwin section 1)

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SORT(1) 										  SORT(1)

NAME
       sort - sort lines of text files

SYNOPSIS
       sort  [-cmus]  [-t separator] [-o output-file] [-T tempdir] [-bdfiMnr] [+POS1 [-POS2]] [-k
       POS1[,POS2]] [file...]
       sort {--help,--version}

DESCRIPTION
       This manual page documents the GNU version of sort.  sort sorts, merges, or  compares  all
       the  lines from the given files, or the standard input if no files are given.  A file name
       of `-' means standard input.  By default, sort writes the results to the standard output.

       sort has three modes of operation: sort (the default), merge, and  check  for  sortedness.
       The following options change the operation mode:

       -c     Check whether the given files are already sorted: if they are not all sorted, print
	      an error message and exit with a status of 1.

       -m     Merge the given files by sorting them as a group.  Each input file  should  already
	      be  individually sorted.	It always works to sort instead of merge; merging is pro-
	      vided because it is faster, in the case where it works.

       A pair of lines is compared as follows: if any key fields have been specified,  sort  com-
       pares  each  pair  of fields, in the order specified on the command line, according to the
       associated ordering options, until a difference is found or no fields are left.

       If any of the global options Mbdfinr are given but no key fields are specified, sort  com-
       pares the entire lines according to the global options.

       Finally,  as  a	last  resort  when all keys compare equal (or if no ordering options were
       specified at all), sort compares the lines byte by byte	in  machine  collating	sequence.
       The  last  resort comparison honors the -r global option.  The -s (stable) option disables
       this last-resort comparison so that lines in which all fields compare equal  are  left  in
       their  original	relative  order.  If no fields or global options are specified, -s has no
       effect.

       GNU sort has no limits on input line length or restrictions on bytes allowed within lines.
       In  addition,  if the final byte of an input file is not a newline, GNU sort silently sup-
       plies one.

       If the environment variable TMPDIR is set, sort uses it as the directory in which  to  put
       temporary  files  instead  of  the default, /tmp.  The -T tempdir option is another way to
       select the directory for temporary files; it overrides the environment variable.

       The following options affect the ordering of output lines.  They may be specified globally
       or  as part of a specific key field.  If no key fields are specified, global options apply
       to comparison of entire lines; otherwise the global options are inherited  by  key  fields
       that do not specify any special options of their own.

       -b     Ignore leading blanks when finding sort keys in each line.

       -d     Sort  in	`phone directory' order: ignore all characters except letters, digits and
	      blanks when sorting.

       -f     Fold lower case characters into the equivalent upper case characters  when  sorting
	      so that, for example, `b' is sorted the same way `B' is.

       -i     Ignore characters outside the ASCII range 040-0176 octal (inclusive) when sorting.

       -M     An  initial string, consisting of any amount of white space, followed by three let-
	      ters abbreviating a month name, is folded to UPPER case and compared in  the  order
	      `JAN' < `FEB' < ... < `DEC.'  Invalid names compare low to valid names.

       -n     Compare  according  to  arithmetic  value  an  initial numeric string consisting of
	      optional white space, an optional - sign, and zero or more digits, optionally  fol-
	      lowed by a decimal point and zero or more digits.

       -r     Reverse the result of comparison, so that lines with greater key values appear ear-
	      lier in the output instead of later.

       Other options are:

       -o output-file
	      Write output to output-file instead of to the standard output.  If  output-file  is
	      one of the input files, sort copies it to a temporary file before sorting and writ-
	      ing the output to output-file.

       -t separator
	      Use character separator as the field separator when finding the sort keys  in  each
	      line.   By  default,  fields are separated by the empty string between a non-white-
	      space character and a whitespace character.  That is to say, given the input line `
	      foo bar', sort breaks it into fields ` foo' and ` bar'.  The field separator is not
	      considered to be part of either the field preceding or the field following it.

       -u     For the default case or the -m option, only output the first of a sequence of lines
	      that  compare  equal.   For  the -c option, check that no pair of consecutive lines
	      compares equal.

       +POS1 [-POS2]
	      Specify a field within each line to use as a sorting key.  The  field  consists  of
	      the  portion of the line starting at POS1 and up to (but not including) POS2 (or to
	      the end of the line if POS2 is not given).  The fields and character positions  are
	      numbered starting with 0.

       -k POS1[,POS2]
	      An  alternate  syntax  for specifying sorting keys.  The fields and character posi-
	      tions are numbered starting with 1.

       A position has the form f.c, where f is the number of the field to use and c is the number
       of  the	first character from the beginning of the field (for +pos) or from the end of the
       previous field (for -pos).  The .c part of a position may be omitted in which case  it  is
       taken  to  be  the  first character in the field.  If the -b option has been given, the .c
       part of a field specification is counted from the first nonblank character  of  the  field
       (for +pos) or from the first nonblank character following the previous field (for -pos).

       A +pos or -pos argument may also have any of the option letters Mbdfinr appended to it, in
       which case the global ordering options are not used for that  particular  field.   The  -b
       option  may  be	independently  attached to either or both of the +pos and -pos parts of a
       field specification, and if it is inherited from the global options it will be attached to
       both.   If a -n or -M option is used, thus implying a -b option, the -b option is taken to
       apply to both the +pos and the -pos parts of a key specification.  Keys may span  multiple
       fields.

       In addition, when GNU sort is invoked with exactly one argument, the following options are
       recognized:

       --help Print a usage message on standard output and exit successfully.

       --version
	      Print version information on standard output then exit successfully.

COMPATIBILITY
       Historical (BSD and System V) implementations of sort have differed in  their  interpreta-
       tion  of  some options, particularly -b, -f, and -n.  GNU sort follows the POSIX behavior,
       which is usually (but not always!) like the System V behavior.  According to POSIX  -n  no
       longer implies -b.  For consistency, -M has been changed in the same way.  This may affect
       the meaning of character positions in field specifications  in  obscure	cases.	 If  this
       bites you the fix is to add an explicit -b.

BUGS
       The different meaning of field numbers depending on whether -k is used is confusing.  It's
       all POSIX's fault!

FSF					GNU Text Utilities				  SORT(1)
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