sort(1p) - phpMan

SORT(1P)                   POSIX Programmer's Manual                  SORT(1P)

PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
NAME
       sort - sort, merge, or sequence check text files
SYNOPSIS
       sort [-m][-o output][-bdfinru][-t char][-k keydef]... [file...]
       sort -c [-bdfinru][-t char][-k keydef][file]

DESCRIPTION
       The sort utility shall perform one of the following functions:
        1. Sort lines of all the named files together and write the result  to
           the specified output.
        2. Merge  lines  of all the named (presorted) files together and write
           the result to the specified output.
        3. Check that a single input file is correctly presorted.
       Comparisons shall be based on one or more sort keys extracted from each
       line  of  input  (or, if no sort keys are specified, the entire line up
       to, but not including, the terminating <newline>), and  shall  be  per-
       formed using the collating sequence of the current locale.
OPTIONS
       The  sort  utility  shall  conform  to  the  Base Definitions volume of
       IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines, and  the
       -k keydef option should follow the -b, -d, -f, -i, -n, and -r options.
       The following options shall be supported:
       -c     Check  that the single input file is ordered as specified by the
              arguments and the collating sequence of the current  locale.  No
              output shall be produced; only the exit code shall be affected.
       -m     Merge  only;  the  input  file  shall  be  assumed to be already
              sorted.
       -o  output
              Specify 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.
       -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, in addition to checking that the input file
              is sorted.

       The  following  options shall override the default ordering rules. When
       ordering options appear independent of any  key  field  specifications,
       the  requested  field  ordering  rules shall be applied globally to all
       sort keys. When attached to a specific  key  (see  -k),  the  specified
       ordering  options  shall  override all global ordering options for that
       key.
       -d     Specify that only <blank>s and alphanumeric characters,  accord-
              ing to the current setting of LC_CTYPE,  shall be significant in
              comparisons. The behavior is undefined for a sort key  to  which
              -i or -n also applies.
       -f     Consider  all  lowercase  characters that have uppercase equiva-
              lents, according to the current setting of LC_CTYPE,  to be  the
              uppercase equivalent for the purposes of comparison.
       -i     Ignore  all  characters that are non-printable, according to the
              current setting of LC_CTYPE.
       -n     Restrict the sort key to an initial numeric  string,  consisting
              of optional <blank>s, optional minus sign, and zero or more dig-
              its with an optional radix character  and  thousands  separators
              (as  defined  in  the  current locale), which shall be sorted by
              arithmetic value. An empty digit  string  shall  be  treated  as
              zero.   Leading zeros and signs on zeros shall not affect order-
              ing.
       -r     Reverse the sense of comparisons.

       The treatment of field separators can be altered using the options:
       -b     Ignore leading <blank>s when determining the starting and ending
              positions  of  a restricted sort key. If the -b option is speci-
              fied before the first -k option, it shall be applied to  all  -k
              options.  Otherwise, the -b option can be attached independently
              to each -k field_start or field_end option-argument (see below).
       -t  char
              Use char as the field separator character;  char  shall  not  be
              considered to be part of a field (although it can be included in
              a sort key). Each occurrence of char shall be  significant  (for
              example,  <char><char>  delimits  an  empty field). If -t is not
              specified, <blank>s shall be used as default  field  separators;
              each  maximal non-empty sequence of <blank>s that follows a non-
              <blank> shall be a field separator.

       Sort keys can be specified using the options:
       -k  keydef
              The keydef argument is a restricted sort key  field  definition.
              The format of this definition is:

              field_start[type][,field_end[type]]
       where field_start and field_end define a key field restricted to a por-
       tion of the line (see the EXTENDED DESCRIPTION section), and type is  a
       modifier from the list of characters 'b', 'd', 'f', 'i', 'n', 'r' . The
       'b' modifier shall behave like the -b option, but shall apply  only  to
       the  field_start or field_end to which it is attached.  The other modi-
       fiers shall behave like the corresponding options, but shall apply only
       to  the  key  field  to  which  they are attached; they shall have this
       effect if specified with field_start, field_end, or both. If any  modi-
       fier  is  attached  to a field_start or to a field_end, no option shall
       apply to either. Implementations shall support  at  least  nine  occur-
       rences  of  the  -k  option, which shall be significant in command line
       order. If no -k option is specified, a default sort key of  the  entire
       line shall be used.
       When  there  are multiple key fields, later keys shall be compared only
       after all earlier keys compare equal. Except  when  the  -u  option  is
       specified,  lines  that  otherwise compare equal shall be 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 com-
       pare equal are written is unspecified.

OPERANDS
       The following operand shall be supported:
       file   A  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 shall be used.

STDIN
       The  standard  input  shall be used only if no file operands are speci-
       fied, or if a file operand is '-' .  See the INPUT FILES section.
INPUT FILES
       The input files shall be text files, except that the sort utility shall
       add  a  <newline>  to  the end of a file ending with an incomplete last
       line.
ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of sort:
       LANG   Provide a default value for the  internationalization  variables
              that  are  unset  or  null.  (See the Base Definitions volume of
              IEEE Std 1003.1-2001, Section  8.2,  Internationalization  Vari-
              ables  for the precedence of internationalization variables used
              to determine the values of locale categories.)
       LC_ALL If set to a non-empty string value, override the values  of  all
              the other internationalization variables.
       LC_COLLATE
              Determine the locale for ordering rules.
       LC_CTYPE
              Determine  the  locale  for  the  interpretation of sequences of
              bytes of text data as characters (for  example,  single-byte  as
              opposed  to  multi-byte characters in arguments and input files)
              and the behavior of character classification for the -b, -d, -f,
              -i, and -n options.
       LC_MESSAGES
              Determine  the  locale  that should be used to affect the format
              and contents of diagnostic messages written to standard error.
       LC_NUMERIC
              Determine the locale for the definition of the  radix  character
              and thousands separator for the -n option.
       NLSPATH
              Determine the location of message catalogs for the processing of
              LC_MESSAGES .

ASYNCHRONOUS EVENTS
       Default.
STDOUT
       Unless the -o or -c options are in effect, the  standard  output  shall
       contain the sorted input.
STDERR
       The  standard  error  shall  be used for diagnostic messages. A warning
       message about correcting an incomplete last line of an input  file  may
       be generated, but need not affect the final exit status.
OUTPUT FILES
       If the -o option is in effect, the sorted input shall be written to the
       file output.
EXTENDED DESCRIPTION
       The notation:

              -k field_start[type][,field_end[type]]
       shall define a key  field  that  begins  at  field_start  and  ends  at
       field_end  inclusive,  unless  field_start  falls beyond the end of the
       line or after field_end, in which case the key field is empty. A  miss-
       ing field_end shall mean the last character of the line.
       A  field comprises a maximal sequence of non-separating characters and,
       in the absence of option -t, any preceding field separator.
       The field_start portion of the keydef option-argument  shall  have  the
       form:

              field_number[.first_character]
       Fields  and characters within fields shall be numbered starting with 1.
       The field_number and first_character pieces,  interpreted  as  positive
       decimal  integers, shall specify the first character to be used as part
       of a sort key. If .first_character is omitted, it shall  refer  to  the
       first character of the field.
       The  field_end  portion  of  the  keydef option-argument shall have the
       form:

              field_number[.last_character]
       The field_number shall be as  described  above  for  field_start.   The
       last_character  piece,  interpreted  as a non-negative decimal integer,
       shall specify the last character to be used as part of the sort key. If
       last_character  evaluates  to  zero  or  .last_character is omitted, it
       shall refer to the last character of the field specified by  field_num-
       ber.
       If  the  -b option or b type modifier is in effect, characters within a
       field shall be counted from the first non- <blank> in the field.  (This
       shall apply separately to first_character and last_character.)
EXIT STATUS
       The following exit values shall be returned:
        0     All  input  files  were output successfully, or -c was specified
              and the input file was correctly sorted.
        1     Under the -c option, the file was not ordered as  specified,  or
              if  the  -c  and -u options were both specified, two input lines
              were found with equal keys.
       >1     An error occurred.

CONSEQUENCES OF ERRORS
       Default.
       The following sections are informative.
APPLICATION USAGE
       The default value for -t, <blank>, has different properties  from,  for
       example, -t "<space>". If a line contains:

              <space><space>foo
       the  following treatment would occur with default separation as opposed
       to specifically selecting a <space>:
                      Field   Default             -t "<space>"
                      1       <space><space>foo   empty
                      2       empty               empty
                      3       empty               foo
       The leading field separator itself is included in a field  when  -t  is
       not  used.  For  example,  this command returns an exit status of zero,
       meaning the input was already sorted:

              sort -c -k 2 <<eof
              y<tab>b
              x<space>a
              eof
       (assuming that a <tab> precedes the <space> in  the  current  collating
       sequence).  The  field  separator is not included in a field when it is
       explicitly set via -t. This is historical  practice  and  allows  usage
       such as:

              sort -t "|" -k 2n <<eof
              Atlanta|425022|Georgia
              Birmingham|284413|Alabama
              Columbia|100385|South Carolina
              eof
       where  the  second  field  can  be correctly sorted numerically without
       regard to the non-numeric field separator.
       The wording in the OPTIONS section clarifies that the -b, -d,  -f,  -i,
       -n,  and -r options have to come before the first sort key specified if
       they are intended to apply  to  all  specified  keys.  The  way  it  is
       described  in  this  volume  of IEEE Std 1003.1-2001 matches historical
       practice, not historical documentation. The results are unspecified  if
       these options are specified after a -k option.
       The  -f option might not work as expected in locales where there is not
       a one-to-one mapping between an uppercase and a lowercase letter.
EXAMPLES
        1. The following command sorts the contents of infile with the  second
           field as the sort key:

           sort -k 2,2 infile
        2. The  following  command  sorts,  in  reverse order, the contents of
           infile1 and infile2, placing the output in outfile  and  using  the
           second character of the second field as the sort key (assuming that
           the first character of the second field is the field separator):

           sort -r -o outfile -k 2.2,2.2 infile1 infile2
        3. The following command sorts the contents  of  infile1  and  infile2
           using the second non- <blank> of the second field as the sort key:

           sort -k 2.2b,2.2b infile1 infile2
        4. The following command prints the System V password file (user data-
           base) sorted by the numeric  user  ID  (the  third  colon-separated
           field):

           sort -t : -k 3,3n /etc/passwd
        5. The  following  command prints the lines of the already sorted file
           infile, suppressing all but one occurrence of lines having the same
           third field:

           sort -um -k 3.1,3.0 infile
RATIONALE
       Examples  in  some historical documentation state that options -um with
       one input file keep the first in each set of  lines  with  equal  keys.
       This  behavior  was deemed to be an implementation artifact and was not
       standardized.
       The -z option was omitted; it is not standard practice on most  systems
       and  is inconsistent with using sort to sort several files individually
       and then merge them together. The text concerning -z in historical doc-
       umentation  appeared to require implementations to determine the proper
       buffer length during the sort phase of operation, but  not  during  the
       merge.
       The  -y  option  was omitted because of non-portability. The -M option,
       present in System V, was omitted because of non-portability in interna-
       tional usage.
       An undocumented -T option exists in some implementations. It is used to
       specify  a  directory  for  intermediate  files.   Implementations  are
       encouraged  to  support  the  use  of  the  TMPDIR environment variable
       instead of adding an option to support this functionality.
       The -k option was added to satisfy two  objections.  First,  the  zero-
       based  counting  used by sort is not consistent with other utility con-
       ventions. Second, it did not meet syntax guideline requirements.
       Historical documentation indicates that "setting -n  implies  -b".  The
       description  of  -n  already  states that optional leading <blank>s are
       tolerated in doing the comparison.   If  -b  is  enabled,  rather  than
       implied,  by -n, this has unusual side effects. When a character offset
       is used in a column of numbers (for example, to sort modulo 100),  that
       offset  is  measured relative to the most significant digit, not to the
       column. Based upon a recommendation from the  author  of  the  original
       sort  utility,  the -b implication has been omitted from this volume of
       IEEE Std 1003.1-2001, and an application wishing to achieve the  previ-
       ously mentioned side effects has to code the -b flag explicitly.
FUTURE DIRECTIONS
       None.
SEE ALSO
       comm, join, uniq, the System Interfaces volume of IEEE Std 1003.1-2001,
       toupper()
COPYRIGHT
       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
       event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard
       is  the  referee document. The original Standard can be obtained online
       at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group                  2003                             SORT(1P)