tsort(1p) — Linux manual page

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

PROLOG         top

       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         top

       tsort — topological sort

SYNOPSIS         top

       tsort [file]

DESCRIPTION         top

       The tsort utility shall write to standard output a totally
       ordered list of items consistent with a partial ordering of items
       contained in the input.

       The application shall ensure that the input consists of pairs of
       items (non-empty strings) separated by <blank> characters. Pairs
       of different items indicate ordering. Pairs of identical items
       indicate presence, but not ordering.

OPTIONS         top

       None.

OPERANDS         top

       The following operand shall be supported:

       file      A pathname of a text file to order. If no file operand
                 is given, the standard input shall be used.

STDIN         top

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

INPUT FILES         top

       The input file shall be a text file.

ENVIRONMENT VARIABLES         top

       The following environment variables shall affect the execution of
       tsort:

       LANG      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base
                 Definitions volume of POSIX.1‐2017, Section 8.2,
                 Internationalization Variables 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_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).

       LC_MESSAGES
                 Determine the locale that should be used to affect the
                 format and contents of diagnostic messages written to
                 standard error.

       NLSPATH   Determine the location of message catalogs for the
                 processing of LC_MESSAGES.

ASYNCHRONOUS EVENTS         top

       Default.

STDOUT         top

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

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       None.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       The following exit values shall be returned:

        0    Successful completion.

       >0    An error occurred.

CONSEQUENCES OF ERRORS         top

       Default.

       The following sections are informative.

APPLICATION USAGE         top

       The LC_COLLATE variable need not affect the actions of tsort.
       The output ordering is not lexicographic, but depends on the
       pairs of items given as input.

EXAMPLES         top

       The command:

           tsort <<EOF
           a b c c d e
           g g
           f g e f
           h h
           EOF

       produces the output:

           a
           b
           c
           d
           e
           f
           g
           h

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       The Base Definitions volume of POSIX.1‐2017, Chapter 8,
       Environment Variables

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 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 .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                         TSORT(1P)

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