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SORT(1)                     General Commands Manual                    SORT(1)

NAME
     sort -- sort or merge text files

SYNOPSIS
     sort [-bcdfHilmnrSsu] [-k field1[,field2]] [-o output] [-R char] [-T dir]
          [-t char] [file ...]

DESCRIPTION
     The sort utility sorts text files by lines.  Comparisons are based on one
     or more sort keys extracted from each line of input, and are performed
     lexicographically.  By default, if keys are not given, sort regards each
     input line as a single field.

     The following options are available:

     -c          Check that the single input file is sorted.  If the file is
                 not sorted, sort produces the appropriate error messages and
                 exits with code 1; otherwise, sort returns 0.  sort -c
                 produces no output.  See also -u.

     -H          Ignored for compatibility with earlier versions of sort.

     -m          Merge only; the input files are assumed to be pre-sorted.

     -o output   The argument given is the name of an output file to be used
                 instead of the standard output.  This file can be the same as
                 one of the input files.

     -S          Don't use stable sort.  Default is to use stable sort.

     -s          Use stable sort, keeps records with equal keys in their
                 original order.  This is the default.  Provided for
                 compatibility with other sort implementations only.

     -T dir      Use dir as the directory for temporary files.  The default is
                 the value specified in the environment variable TMPDIR or
                 /tmp if TMPDIR is not defined.

     -u          Unique: suppress all but one in each set of lines having
                 equal keys.  If used with the -c option, check that there are
                 no lines with duplicate keys.

     The following options override the default ordering rules.  When ordering
     options appear independent of key field specifications, the requested
     field ordering rules are applied globally to all sort keys.  When
     attached to a specific key (see -k), the ordering options override all
     global ordering options for that key.

     -d          Only blank space and alphanumeric characters are used in
                 making comparisons.

     -f          Considers all lowercase characters that have uppercase
                 equivalents to be the same for purposes of comparison.

     -i          Ignore all non-printable characters.

     -l          Sort by the string length of the field, not by the field
                 itself.

     -n          An initial numeric string, consisting of optional blank
                 space, optional plus or minus sign, and zero or more digits
                 (including decimal point) is sorted by arithmetic value.
                 (The -n option no longer implies the -b option.)

     -r          Reverse the sense of comparisons.

     The treatment of field separators can be altered using these options:

     -b          Ignores leading blank space when determining the start and
                 end of a restricted sort key.  A -b option specified before
                 the first -k option applies globally to all -k options.
                 Otherwise, the -b option can be attached independently to
                 each field argument of the -k option (see below).  Note that
                 the -b option has no effect unless key fields are specified.

     -t char     char is used as the field separator character.  The initial
                 char is not considered to be part of a field when determining
                 key offsets (see below).  Each occurrence of char is
                 significant (for example, ``charchar'' delimits an empty
                 field).  If -t is not specified, the default field separator
                 is a sequence of blank-space characters, and consecutive
                 blank spaces do not delimit an empty field; further, the
                 initial blank space is considered part of a field when
                 determining key offsets.

     -R char     char is used as the record separator character.  This should
                 be used with discretion; -R <alphanumeric> usually produces
                 undesirable results.  The default record separator is
                 newline.

     -k field1[,field2]
                 Designates the starting position, field1, and optional ending
                 position, field2, of a key field.  The -k option replaces the
                 obsolescent options +pos1 and -pos2.

     The following operands are available:

     file          The pathname of a file to be sorted, merged, or checked.
                   If no file operands are specified, or if a file operand is
                   -, the standard input is used.

     A field is defined as a minimal sequence of characters followed by a
     field separator or a newline character.  By default, the first blank
     space of a sequence of blank spaces acts as the field separator.  All
     blank spaces in a sequence of blank spaces are considered as part of the
     next field; for example, all blank spaces at the beginning of a line are
     considered to be part of the first field.

     Fields are specified by the -k field1[,field2] argument.  A missing
     field2 argument defaults to the end of a line.

     The arguments field1 and field2 have the form m.n and can be followed by
     one or more of the letters b, d, f, i, l, n, and r, which correspond to
     the options discussed above.  A field1 position specified by m.n (m, n >
     0) is interpreted as the nth character in the mth field.  A missing .n in
     field1 means `.1', indicating the first character of the mth field; if
     the -b option is in effect, n is counted from the first non-blank
     character in the mth field; m.1b refers to the first non-blank character
     in the mth field.

     A field2 position specified by m.n is interpreted as the nth character
     (including separators) of the mth field.  A missing .n indicates the last
     character of the mth field; m = 0 designates the end of a line.  Thus the
     option -k v.x,w.y is synonymous with the obsolescent option
     +v-1.x-1-w-1.y; when y is omitted, -k v.x,w is synonymous with
     +v-1.x-1-w+1.0.  The obsolescent +pos1 -pos2 option is still supported,
     except for -w.0b, which has no -k equivalent.

ENVIRONMENT
     If the following environment variable exists, it is used by sort.

     TMPDIR           sort uses the contents of the TMPDIR environment
                      variable as the path in which to store temporary files.

FILES
     /tmp/sort.*        Default temporary files.
     outputNUMBER       Temporary file which is used for output if output
                        already exists.  Once sorting is finished, this file
                        replaces output (via link(2) and unlink(2)).

EXIT STATUS
     Sort exits with one of the following values:
     0     Normal behavior.
     1     On disorder (or non-uniqueness) with the -c option
     2     An error occurred.

SEE ALSO
     comm(1), join(1), uniq(1), qsort(3), radixsort(3)

HISTORY
     A sort command appeared in Version 5 AT&T UNIX.  This sort implementation
     appeared in 4.4BSD and is used since NetBSD 1.6.

BUGS
     Posix requires the locale's thousands separator be ignored in numbers.
     It may be faster to sort very large files in pieces and then explicitly
     merge them.

NOTES
     This sort has no limits on input line length (other than imposed by
     available memory) or any restrictions on bytes allowed within lines.

     To protect data sort -o calls link(2) and unlink(2), and thus fails on
     protected directories.

     Input files should be text files.  If file doesn't end with record
     separator (which is typically newline), the sort utility silently
     supplies one.

     The current sort uses lexicographic radix sorting, which requires that
     sort keys be kept in memory (as opposed to previous versions which used
     quick and merge sorts and did not.)  Thus performance depends highly on
     efficient choice of sort keys, and the -b option and the field2 argument
     of the -k option should be used whenever possible.  Similarly, sort -k1f
     is equivalent to sort -f and may take twice as long.

NetBSD 7.1.2                     May 29, 2013                     NetBSD 7.1.2