SORT(1) 						      General Commands Manual							   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 provided 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 compares 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 compares 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 supplies 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 letters 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 followed by a decimal point and zero or more digits.

       -r     Reverse the result of comparison, so that lines with greater key values appear earlier 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 tempo-
	      rary file before sorting and writing 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-whitespace 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 positions 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  non-
       blank 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 speci-
       fication,  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 interpretation 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	specifica-
       tions 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)