SORT(1)                                                   SORT(1)

     NAME
          sort - sort and/or merge files

     SYNOPSIS
          sort [ -cmuMbdfinrwtx ] [ +pos1 [ -pos2 ] ...  ] ...  [ -k
          pos1 [ ,pos2 ] ] ...
                [ -o output ] [ -T dir ...  ] [ option ...  ] [ file
          ...  ]

     DESCRIPTION
          Sort sorts lines of all the files together and writes the
          result on the standard output.  If no input files are named,
          the standard input is sorted.

          The default sort key is an entire line.  Default ordering is
          lexicographic by runes.  The ordering is affected globally
          by the following options, one or more of which may appear.

          -M   Compare as months.  The first three non-white space
               characters of the field are folded to upper case and
               compared so that `JAN' precedes `FEB', etc.  Invalid
               fields compare low to `JAN'.

          -b   Ignore leading white space (spaces and tabs) in field
               comparisons.

          -d   `Phone directory' order: only letters, accented let-
               ters, digits and white space are significant in compar-
               isons.

          -f   Fold lower case letters onto upper case.  Accented
               characters are folded to their non-accented upper case
               form.

          -i   Ignore characters outside the ASCII range 040-0176 in
               non-numeric comparisons.

          -w   Like -i, but ignore only tabs and spaces.

          -n   An initial numeric string, consisting of optional white
               space, optional plus or minus sign, and zero or more
               digits with optional decimal point, is sorted by arith-
               metic value.

          -g   Numbers, like -n but with optional e-style exponents,
               are sorted by value.

          -r   Reverse the sense of comparisons.

          -tx  `Tab character' separating fields is x.

     SORT(1)                                                   SORT(1)

          The notation +pos1 -pos2 restricts a sort key to a field
          beginning at pos1 and ending just before pos2. Pos1 and pos2
          each have the form m.n, optionally followed by one or more
          of the flags Mbdfginr, where m tells a number of fields to
          skip from the beginning of the line and n tells a number of
          characters to skip further.  If any flags are present they
          override all the global ordering options for this key.  A
          missing .n means .0; a missing -pos2 means the end of the
          line.  Under the -tx option, fields are strings separated by
          x; otherwise fields are non-empty strings separated by white
          space.  White space before a field is part of the field,
          except under option -b.  A b flag may be attached indepen-
          dently to pos1 and pos2.

          The notation -k pos1[,pos2] is how POSIX sort defines
          fields: pos1 and pos2 have the same format but different
          meanings.  The value of m is origin 1 instead of origin 0
          and a missing .n in pos2 is the end of the field.

          When there are multiple sort keys, later keys are compared
          only after all earlier keys compare equal.  Lines that oth-
          erwise compare equal are ordered with all bytes significant.

          These option arguments are also understood:

          -c         Check that the single input file is sorted
                     according to the ordering rules; give no output
                     unless the file is out of sort.

          -m         Merge; assume the input files are already sorted.

          -u         Suppress all but one in each set of equal lines.
                     Ignored bytes and bytes outside keys do not par-
                     ticipate in this comparison.

          -o         The next argument is the name of an output file
                     to use instead of the standard output.  This file
                     may be the same as one of the inputs.

          -Tdir      Put temporary files in dir rather than in /tmp.

     EXAMPLES
          `sort -u +0f +0 list'
               Print in alphabetical order all the unique spellings in
               a list of words where capitalized words differ from
               uncapitalized.

          `sort -t: +1 /adm/users'
               Print the users file sorted by user name (the second
               colon-separated field).

          `sort -umM dates'

     SORT(1)                                                   SORT(1)

               Print the first instance of each month in an already
               sorted file.  Options -um with just one input file make
               the choice of a unique representative from a set of
               equal lines predictable.

          grep -n '^' input | sort -t: +1f +0n | sed 's/[0-9]*://'
               A stable sort: input lines that compare equal will come
               out in their original order.

     FILES
          /tmp/sort.<pid>.<ordinal>

     SOURCE
          /sys/src/cmd/sort.c

     SEE ALSO
          uniq(1), look(1)

     DIAGNOSTICS
          Sort comments and exits with non-null status for various
          trouble conditions and for disorder discovered under option
          -c.

     BUGS
          An external null character can be confused with an inter-
          nally generated end-of-field character.  The result can make
          a sub-field not sort less than a longer field.

          Some of the options, e.g.  -M, are hopelessly provincial.