Sort(3)               User Contributed Perl Documentation              Sort(3)

       File::Sort - Sort a file or merge sort multiple files

         use File::Sort qw(sort_file);
           I => [qw(file_1 file_2)],
           o => 'file_new', k => '5.3,5.5rn', -t => '⎪'

         sort_file('file1', 'file1.sorted');

       This module sorts text files by lines (or records).  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 sort is a merge
       sort.  If you don't like that, feel free to change it.


       The following options are available, and are passed in the hash
       reference passed to the function in the format:

         OPTION => VALUE

       Where an option can take multiple values (like I, k, and pos), values
       may be passed via an anonymous array:

         OPTION => [VALUE1, VALUE2]

       Where the OPTION is a switch, it should be passed a boolean VALUE of 1
       or 0.

       This interface will always be supported, though a more perlish
       interface may be offered in the future, as well.  This interface is
       basically a mapping of the command-line options to the Unix sort

       I INPUT
           Pass in the input file(s).  This can be either a single string with
           the filename, or an array reference containing multiple filename

       c   Check that single input fle is ordered as specified by the
           arguments and the collating sequence of the current locale.  No
           output is produced; only the exit code is affected.

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

       o OUTPUT
           Specify the name of an OUTPUT file to be used instead of the
           standard output.

       u   Unique: Suppresses all but one in each set of lines having equal
           keys.  If used with the c option check that there are no lines with
           consecutive lines with duplicate keys, in addition to checking that
           the input file is sorted.

           Maximum number of lines (records) read before writing to temp file.
           Default is 200,000. This may eventually change to be kbytes instead
           of lines.  Lines was easier to implement.  Can also specify with
           MAX_SORT_RECORDS environment variable.

           Maximum number of temp files to be held open at once.  Default to
           40, as older Windows ports had quite a small limit.  Can also
           specify with MAX_SORT_FILES environment variable.  No temp files
           will be used at all if MAX_SORT_RECORDS is never reached.

       D   Send debugging information to STDERR.  Behavior subject to change.

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

       d   Specify that only blank characters and alphanumeric characters,
           according to the current locale setting, are significant in
           comparisons.  d overrides i.

       f   Consider all lower-case characters that have upper-case
           equivalents, according to the current locale setting, to be the
           upper-case equivalent for the purposes of comparison.

       i   Ignores all characters that are non-printable, according to the
           current locale setting.

       n   Does numeric instead of string compare, using whatever perl
           considers to be a number in numeric comparisons.

       r   Reverse the sense of the comparisons.

       b   Ignore leading blank characters when determining the starting and
           ending positions of a restricted sort key.  If the b option is
           specified before the first k option, it is applied to all k
           options.  Otherwise, the b option can be attached indepently to
           each field_start or field_end option argument (see below).

       t STRING
           Use STRING as the field separator character; char is not considered
           to be part of a field (although it can be included in a sort key).
           Each occurrence of char is significant (for example, <char><char>
           delimits an empty field).  If t is not specified, blank characters
           are used as default field separators; each maximal non-empty
           sequence of blank characters that follows a non-blank character is
           a field separator.

       X STRING
           Same as t, but STRING is interpreted as a Perl regular expression
           instead.  Do not escape any characters (/ characters need to be
           escaped internally, and will be escaped for you).

           The string matched by STRING is not included in the fields
           themselves, unless demanded by perl's regex and split semantics
           (e.g., regexes in parentheses will add that matched expression as
           an extra field).  See the perlre manpage and the split entry in the
           perlfunc manpage.

       R STRING
           Record separator, defaults to newline.

       k pos1[,pos2]
           The keydef argument is a restricted sort key field definition. The
           format of this definition is:


           where field_start and field_end define a key field restricted to a
           portion of the line, and type is a modifier from the list of
           characters b, d, f, i, n, r.  The b modifier behaves like the b
           option, but applies only to the field_start or field_end to which
           it is attached. The other modifiers behave like the corresponding
           options, but apply only to the key field to which they are
           attached; they have this effect if specified with field_start,
           field_end, or both.  If any modifier is attached to a field_start
           or a field_end, no option applies to either.

           Occurrences of the k option are significant in command line order.
           If no k option is specified, a default sort key of the entire line
           is used.  When there are multiple keys fields, later keys are
           compared only after all earlier keys compare equal.

           Except when the u option is specified, lines that otherwise compare
           equal are ordered as if none of the options d, f, i, n or k were
           present (but with r still in effect, if it was specified) and with
           all bytes in the lines significant to the comparison.  The order in
           which lines that still compare equal are written is unspecified.

       pos +pos1 [-pos2]
           Similar to k, these are mostly obsolete switches, but some people
           like them and want to use them.  Usage is:

               +field_start[.first_char][type] [-field_end[.last_char][type]]

           Where field_end in k specified the last position to be included, it
           specifes the last position to NOT be included.  Also, numbers are
           counted from 0 instead of 1.  pos2 must immediately follow
           corresponding +pos1.  The rest should be the same as the k option.

           Mixing +pos1 pos2 with k is allowed, but will result in all of the
           +pos1 pos2 options being ordered AFTER the k options.  It is best
           if you Don't Do That.  Pick one and stick with it.

           Here are some equivalencies:

               pos => '+1 -2'              ->  k => '2,2'
               pos => '+1.1 -1.2'          ->  k => '2.2,2.2'
               pos => ['+1 -2', '+3 -5']   ->  k => ['2,2', '4,5']
               pos => ['+2', '+0b -1']     ->  k => ['3', '1b,1']
               pos => '+2.1 -2.4'          ->  k => '3.2,3.4'
               pos => '+2.0 -3.0'          ->  k => '3.1,4.0'

       Not Implemented

       If the options are not listed as implemented above, or are not listed
       in TODO below, they are not in the plan for implementation.  This
       includes T and z.

       Sort file by straight string compare of each line, sending output to

           use File::Sort qw(sort_file);

       Sort contents of file by second key in file.

           sort_file({k => 2, I => 'file'});

       Sort, in reverse order, contents of file1 and file2, placing output in
       outfile and using second character of second field as the sort key.

               r => 1, k => '2.2,2.2', o => 'outfile',
               I => ['file1', 'file2']

       Same sort but sorting numerically on characters 3 through 5 of the
       fifth field first, and only return records with unique keys.

               u => 1, r => 1, k => ['5.3,5.5rn', '2.2,2.2'],
               o => 'outfile', I => ['file1', 'file2']

       Print passwd(4) file sorted by numeric user ID.

           sort_file({t => ':', k => '3n', I => '/etc/passwd'});

       For the anal sysadmin, check that passwd(4) file is sorted by numeric
       user ID.

           sort_file({c => 1, t => ':', k => '3n', I => '/etc/passwd'});

       Note that if you change the locale settings after the program has
       started up, you must call setlocale() for the new settings to take
       effect.  For example:

           # get constants
           use POSIX 'locale_h';

           # e.g., blank out locale
           $ENV{LC_ALL} = $ENV{LANG} = '';

           # use new ENV settings
           setlocale(LC_CTYPE, '');
           setlocale(LC_COLLATE, '');

           Determine the locale for ordering rules.

           Determine the locale for the interpretation of sequences of bytes
           of text data as characters (for example, single- versus multi-byte
           characters in arguments and input files) and the behaviour of
           character classification for the b, d, f, i and n options.

           Default is 200,000.  Maximum number of records to use before
           writing to a temp file.  Overriden by y option.

           Maximum number of open temp files to use before merging open temp
           files.  Overriden by F option.

       Exports sort_file on request.

       Better debugging and error reporting

       Performance hit with -u

       Do bytes instead of lines

       Better test suite

       Switch for turning off locale ... ?

       v1.01, Monday, January 14, 2002
           Change license to be that of Perl.

       v1.00, Tuesday, November 13, 2001
           Long overdue release.

           Add O_TRUNC to output open (D'oh!).

           Played with somem of the -k options (Marco A. Romero).

           Fix filehandle close test of STDOUT (Gael Marziou).

           Some cleanup.

       v0.91, Saturday, February 12, 2000
           Closed all files in so they could be unlinked on some
           platforms.  (Hubert Toullec)

           Documented I option.  (Hubert Toullec)

           Removed O_EXCL flag from sort_file.

           Fixed bug in sorting multiple files.  (Paul Eckert)

       v0.90, Friday, April 30, 1999
           Complete rewrite.  Took the code from this module to write sort
           utility for PPT project, then brought changes back over.  As a
           result the interface has changed slightly, mostly in regard to what
           letters are used for options, but there are also some key
           behavioral differences.  If you need the old interface, the old
           module will remain on CPAN, but will not be supported.  Sorry for
           any inconvenience this may cause.  The good news is that it should
           not be too difficult to update your code to use the new interface.

           Fixed bug with unique option (didn't work :).

           Switched to sysopen for better portability.

           Print to STDOUT if no output file supplied.

           Added c option to check sorting.

       v0.18 (31 January 1998)
           Tests 3 and 4 failed because we hit the open file limit in the
           standard Windows port of perl5.004_02 (50).  Adjusted the default
           for total number of temp files from 50 to 40 (leave room for other
           open files), changed docs.  (Mike Blazer, Gurusamy Sarathy)

       v0.17 (30 December 1998)
           Fixed bug in _merge_files that tried to open a passed IO::File

           Fixed up docs and did some more tests and benchmarks.

       v0.16 (24 December 1998)
           One year between releases was too long.  I made changes Miko
           O'Sullivan wanted, and I didn't even know I had made them.

           Also now use IO::File to create temp files, so the TMPDIR option is
           no longer supported.  Hopefully made the whole thing more robust
           and faster, while supporting more options for sorting, including
           delimited sorts, and arbitrary sorts.

           Made CHUNK default a lot larger, which improves performance.  On
           low-memory systems, or where (e.g.) the MacPerl binary is not
           allocated much RAM, it might need to be lowered.

       v0.11 (04 January 1998)
           More cleanup; fixed special case of no linebreak on last line;
           wrote test suite; fixed warning for redefined subs (sort1 and

       v0.10 (03 January 1998)
           Some cleanup; made it not subject to system file limitations;
           separated many parts out into separate functions.

       v0.03 (23 December 1997)
           Added reverse and numeric sorting options.

       v0.02 (19 December 1997)
           Added unique and merge-only options.

       v0.01 (18 December 1997)
           First release.

       Mike Blazer <>, Vicki Brown <>, Tom
       Christiansen <>, Albert Dvornik <>, Paul
       Eckert <>, Gene Hsu <>, Andrew M.
       Langmead <>, Gael Marziou <>, Brian
       L. Matthews <>, Rich Morin <>, Matthias
       Neeracher <>, Miko O'Sullivan <>, Tom
       Phoneix <>, Marco A. Romero <>,
       Gurusamy Sarathy <>, Hubert Toullec

       Chris Nandor <>,

       Copyright (c) 1997-2002 Chris Nandor.  All rights reserved.  This
       program is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself.

       v1.01, Monday, January 14, 2002

       sort(1), locale, PPT project, <URL:>.

3rd Berkeley Distribution    perl 5.005, patch 03                      Sort(3)