1TSORT(1P)                  POSIX Programmer's Manual                 TSORT(1P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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11

NAME

13       tsort — topological sort
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SYNOPSIS

16       tsort [file]
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DESCRIPTION

19       The tsort utility shall write to standard output a totally ordered list
20       of  items  consistent with a partial ordering of items contained in the
21       input.
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23       The application shall ensure that the input consists of pairs of  items
24       (non-empty strings) separated by <blank> characters. Pairs of different
25       items indicate ordering. Pairs of identical  items  indicate  presence,
26       but not ordering.
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OPTIONS

29       None.
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OPERANDS

32       The following operand shall be supported:
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34       file      A  pathname  of  a  text file to order. If no file operand is
35                 given, the standard input shall be used.
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STDIN

38       The standard input shall be used if no file operand is  specified,  and
39       shall  be used if the file operand is '−' and the implementation treats
40       the '−' as meaning standard input.  Otherwise, the standard input shall
41       not be used.  See the INPUT FILES section.
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INPUT FILES

44       The input file shall be a text file.
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ENVIRONMENT VARIABLES

47       The  following  environment  variables  shall  affect  the execution of
48       tsort:
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50       LANG      Provide a default value for  the  internationalization  vari‐
51                 ables  that are unset or null. (See the Base Definitions vol‐
52                 ume of POSIX.1‐2008, Section 8.2, Internationalization  Vari‐
53                 ables  for  the  precedence of internationalization variables
54                 used to determine the values of locale categories.)
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56       LC_ALL    If set to a non-empty string value, override  the  values  of
57                 all the other internationalization variables.
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59       LC_CTYPE  Determine  the  locale for the interpretation of sequences of
60                 bytes of text data as characters (for example, single-byte as
61                 opposed  to  multi-byte  characters  in  arguments  and input
62                 files).
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64       LC_MESSAGES
65                 Determine the locale that should be used to affect the format
66                 and  contents  of  diagnostic  messages  written  to standard
67                 error.
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69       NLSPATH   Determine the location of message catalogs for the processing
70                 of LC_MESSAGES.
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ASYNCHRONOUS EVENTS

73       Default.
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STDOUT

76       The  standard  output shall be a text file consisting of the order list
77       produced from the partially ordered input.
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STDERR

80       The standard error shall be used only for diagnostic messages.
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OUTPUT FILES

83       None.
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EXTENDED DESCRIPTION

86       None.
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EXIT STATUS

89       The following exit values shall be returned:
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91        0    Successful completion.
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93       >0    An error occurred.
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CONSEQUENCES OF ERRORS

96       Default.
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98       The following sections are informative.
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APPLICATION USAGE

101       The LC_COLLATE variable need not affect the actions of tsort.  The out‐
102       put  ordering  is  not lexicographic, but depends on the pairs of items
103       given as input.
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EXAMPLES

106       The command:
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108           tsort <<EOF
109           a b c c d e
110           g g
111           f g e f
112           h h
113           EOF
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115       produces the output:
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117           a
118           b
119           c
120           d
121           e
122           f
123           g
124           h
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RATIONALE

127       None.
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FUTURE DIRECTIONS

130       None.
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SEE ALSO

133       The Base Definitions volume of  POSIX.1‐2008,  Chapter  8,  Environment
134       Variables
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137       Portions  of  this text are reprinted and reproduced in electronic form
138       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
139       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
140       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
141       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
142       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  In  the
143       event of any discrepancy between this version and the original IEEE and
144       The Open Group Standard, the original IEEE and The Open Group  Standard
145       is  the  referee document. The original Standard can be obtained online
146       at http://www.unix.org/online.html .
147
148       Any typographical or formatting errors that appear  in  this  page  are
149       most likely to have been introduced during the conversion of the source
150       files to man page format. To report such errors,  see  https://www.ker
151       nel.org/doc/man-pages/reporting_bugs.html .
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155IEEE/The Open Group                  2013                            TSORT(1P)
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