SORT(1)                     General Commands Manual                    SORT(1)


     sort - sort, merge, or sequence check text and binary files


     sort [-bCcdfgHhiMmnRrsuVz] [-k field1[,field2]] [-o output] [-S size]
          [-T dir] [-t char] [file ...]


     The sort utility sorts text and binary files by lines.  A line is a
     record separated from the subsequent record by a newline (default) or NUL
     '\0' character (-z option).  A record can contain any printable or
     unprintable characters.  Comparisons are based on one or more sort keys
     extracted from each line of input, and are performed lexicographically,
     according to the current locale's collating rules and the specified
     command-line options that can tune the actual sorting behavior.  By
     default, if keys are not given, sort uses entire lines for comparison.

     If no file is specified, or if file is `-', the standard input is used.

     The options are as follows:

     -C, --check=silent|quiet
             Check that the single input file is sorted.  If it is, exit 0; if
             it's not, exit 1.  In either case, produce no output.

     -c, --check
             Like -C, but additionally write a message to stderr if the input
             file is not sorted.

     -m, --merge
             Merge only; the input files are assumed to be pre-sorted.  If
             they are not sorted, the output order is undefined.

     -o output, --output=output
             Write the output to the output file instead of the standard
             output.  This file can be the same as one of the input files.

     -S size, --buffer-size=size
             Use a memory buffer no larger than size.  The modifiers %, b, K,
             M, G, T, P, E, Z, and Y can be used.  If no memory limit is
             specified, sort may use up to about 90% of available memory.  If
             the input is too big to fit into the memory buffer, temporary
             files are used.

     -s      Stable sort; maintains the original record order of records that
             have an equal key.  This is a non-standard feature, but it is
             widely accepted and used.

     -T dir, --temporary-directory=dir
             Store temporary files in the directory dir.  The default path is
             the value of the environment variable TMPDIR or /tmp if TMPDIR is
             not defined.

     -u, --unique
             Unique: suppress all but one in each set of lines having equal
             keys.  This option implies a stable sort (see below).  If used
             with -C or -c, sort also checks that there are no lines with
             duplicate keys.

     The following options override the default ordering rules.  If ordering
     options appear before the first -k option, they apply globally to all
     sort keys.  When attached to a specific key (see -k), the ordering
     options override all global ordering options for that key.  Note that the
     ordering options intended to apply globally should not appear after -k or
     results may be unexpected.

     -d, --dictionary-order
             Consider only blank spaces and alphanumeric characters in

     -f, --ignore-case
             Consider all lowercase characters that have uppercase equivalents
             to be the same for purposes of comparison.

     -g, --general-numeric-sort, --sort=general-numeric
             Sort by general numerical value.  As opposed to -n, this option
             handles general floating points.  It has a more permissive format
             than that allowed by -n but it has a significant performance

     -h, --human-numeric-sort, --sort=human-numeric
             Sort by numerical value, but take into account the SI suffix, if
             present.  Sorts first by numeric sign (negative, zero, or
             positive); then by SI suffix (either empty, or `k' or `K', or one
             of `MGTPEZY', in that order); and finally by numeric value.  The
             SI suffix must immediately follow the number.  For example,
             '12345K' sorts before '1M', because M is "larger" than K.  This
             sort option is useful for sorting the output of a single
             invocation of 'df' command with -h or -H options (human-

     -i, --ignore-nonprinting
             Ignore all non-printable characters.

     -M, --month-sort, --sort=month
             Sort by month abbreviations.  Unknown strings are considered
             smaller than valid month names.

     -n, --numeric-sort, --sort=numeric
             An initial numeric string, consisting of optional blank space,
             optional minus sign, and zero or more digits (including decimal
             point) is sorted by arithmetic value.  Leading blank characters
             are ignored.

     -R, --random-sort, --sort=random
             Sort lines in random order.  This is a random permutation of the
             inputs with the exception that equal keys sort together.  It is
             implemented by hashing the input keys and sorting the hash
             values.  The hash function is randomized with data from
             arc4random_buf(3), or by file content if one is specified via
             --random-source.  If multiple sort fields are specified, the same
             random hash function is used for all of them.

     -r, --reverse
             Sort in reverse order.

     -V, --version-sort
             Sort version numbers.  The input lines are treated as file names
             in form PREFIX VERSION SUFFIX, where SUFFIX matches the regular
             expression "(.([A-Za-z~][A-Za-z0-9~]*)?)*".  The files are
             compared by their prefixes and versions (leading zeros are
             ignored in version numbers, see example below).  If an input
             string does not match the pattern, then it is compared using the
             byte compare function.  All string comparisons are performed in
             the C locale.

             For example:

                   $ ls sort* | sort -V

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

     -b, --ignore-leading-blanks
             Ignore leading blank space when determining the start and end of
             a restricted sort key (see -k).  If -b is specified before the
             first -k option, it applies globally to all key specifications.
             Otherwise, -b can be attached independently to each field
             argument of the key specifications.  Note that -b should not
             appear after -k, and that it has no effect unless key fields are

     -k field1[,field2], --key=field1[,field2]
             Define a restricted sort key that has the starting position
             field1, and optional ending position field2 of a key field.  The
             -k option may be specified multiple times, in which case
             subsequent keys are compared after earlier keys compare equal.
             The -k option replaces the obsolete options +pos1 and -pos2, but
             the old notation is also supported.

     -t char, --field-separator=char
             Use char as the field separator character.  The initial char is
             not considered to be part of a field when determining key
             offsets.  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.  To use NUL as field separator, use
             -t '\0'.

     -z, --zero-terminated
             Use NUL as the record separator.  By default, records in the
             files are expected to be separated by the newline characters.
             With this option, NUL ('\0') is used as the record separator

     Other options:

             Specify maximum number of files that can be opened by sort at
             once.  This option affects behavior when having many input files
             or using temporary files.  The minimum value is 2.  The default
             value is 16.

             Use program to compress temporary files.  When invoked with no
             arguments, program must compress standard input to standard
             output.  When called with the -d option, it must decompress
             standard input to standard output.  If program fails, sort will
             exit with an error.  The compress(1) and gzip(1) utilities meet
             these requirements.

             Print some extra information about the sorting process to the
             standard output.

             Take the input file list from the file filename.  The file names
             must be separated by NUL (like the output produced by the command
             "find ... -print0").

             Try to use heap sort, if the sort specifications allow.  This
             sort algorithm cannot be used with -u and -s.

     --help  Print the help text and exit.

     --mergesort, -H
             Use mergesort.  This is a universal algorithm that can always be
             used, but it is not always the fastest.

     --mmap  Try to use file memory mapping system call.  It may increase
             speed in some cases.

             Try to use quick sort, if the sort specifications allow.  This
             sort algorithm cannot be used with -u and -s.

             Try to use radix sort, if the sort specifications allow.  The
             radix sort can only be used for trivial locales (C and POSIX),
             and it cannot be used for numeric or month sort.  Radix sort is
             very fast and stable.

             For random sort, the contents of filename are used as the source
             of the `seed' data for the hash function.  Two invocations of
             random sort with the same seed data will use produce the same
             result if the input is also identical.  By default, the
             arc4random_buf(3) function is used instead.

             Print the version and exit.

     A field is defined as a maximal sequence of characters other than the
     field separator and record separator (newline by default).  Initial blank
     spaces are included in the field unless -b has been specified; the first
     blank space of a sequence of blank spaces acts as the field separator and
     is included in the field (unless -t is specified).  For example, by
     default 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] option.  If field2 is
     missing, the end of the key defaults to the end of the line.

     The arguments field1 and field2 have the form m.n (m,n > 0) and can be
     followed by one or more of the modifiers b, d, f, i, n, g, M and r, which
     correspond to the options discussed above.  When b is specified it
     applies only to field1 or field2 where it is specified while the rest of
     the modifiers apply to the whole key field regardless if they are
     specified only with field1 or field2 or both.  A field1 position
     specified by m.n is interpreted as the nth character from the beginning
     of 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.  1.n refers to the nth
     character from the beginning of the line; if n is greater than the length
     of the line, the field is taken to be empty.

     nth positions are always counted from the field beginning, even if the
     field is shorter than the number of specified positions.  Thus, the key
     can really start from a position in a subsequent field.

     A field2 position specified by m.n is interpreted as the nth character
     (including separators) from the beginning 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 obsolete
     option +v-1.x-1 -w-1.y; when y is omitted, -k v.x,w is synonymous with
     +v-1.x-1 -w.0.  The obsolete +pos1 -pos2 option is still supported,
     except for -w.0b, which has no -k equivalent.


                 If defined -t will not override the locale numeric symbols,
                 that is, thousand separators and decimal separators.  By
                 default, if we specify -t with the same symbol as the
                 thousand separator or decimal point, the symbol will be
                 treated as the field separator.  Older behavior was less
                 definite: the symbol was treated as both field separator and
                 numeric separator, simultaneously.  This environment variable
                 enables the old behavior.

     LANG        Used as a last resort to determine different kinds of locale-
                 specific behavior if neither the respective environment
                 variable nor LC_ALL are set.

     LC_ALL      Locale settings that override all of the other locale
                 settings.  This environment variable can be used to set all
                 these settings to the same value at once.

     LC_COLLATE  Locale settings to be used to determine the collation for
                 sorting records.

     LC_CTYPE    Locale settings to be used to case conversion and
                 classification of characters, that is, which characters are
                 considered whitespaces, etc.

                 Locale settings that determine the language of output
                 messages that sort prints out.

     LC_NUMERIC  Locale settings that determine the number format used in
                 numeric sort.

     LC_TIME     Locale settings that determine the month format used in month

     TMPDIR      Path to the directory in which temporary files will be
                 stored.  Note that TMPDIR may be overridden by the -T option.


     /tmp/.bsdsort.PID.*               Temporary files.


     The sort utility exits with one of the following values:

           0       Successfully sorted the input files or if used with -C or
                   -c, the input file already met the sorting criteria.
           1       On disorder (or non-uniqueness) with the -C or -c options.
           2       An error occurred.


     comm(1), join(1), uniq(1)


     The sort utility is compliant with the IEEE Std 1003.1-2008 ("POSIX.1")

     The flags [-gHhiMRSsTVz] are extensions to that specification.

     All long options are extensions to the specification.  Some are provided
     for compatibility with GNU sort, others are specific to this

     Some implementations of sort honor the -b option even when no key fields
     are specified.  This implementation follows historic practice and IEEE
     Std 1003.1-2008 ("POSIX.1") in only honoring -b when it precedes a key

     The historic practice of allowing the -o option to appear after the file
     is supported for compatibility with older versions of sort.

     The historic key notations +pos1 and -pos2 are supported for
     compatibility with older versions of sort but their use is highly


     A sort command appeared in Version 3 AT&T UNIX.


     Gabor Kovesdan <>
     Oleg Moskalenko <>


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

     The performance depends highly on locale settings, efficient choice of
     sort keys and key complexity.  The fastest sort is with the C locale, on
     whole lines, with option -s.  In general, the C locale is the fastest,
     followed by single-byte locales with multi-byte locales being the
     slowest.  The correct collation order respected in all cases.  For the
     key specification, the simpler to process the lines the faster the search
     will be.

     When sorting by arithmetic value, using -n results in much better
     performance than -g so its use is encouraged whenever possible.

OpenBSD 6.4                      June 10, 2017                     OpenBSD 6.4

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