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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
TSORT(1P) POSIX Programmer's Manual TSORT(1P)
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.
tsort — topological sort
tsort [file]
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.
None.
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.
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.
The input file shall be a text file.
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.1‐2008, 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.
Default.
The standard output shall be a text file consisting of the order list
produced from the partially ordered input.
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
Default.
The following sections are informative.
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.
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
None.
None.
The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
Variables
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/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 2013 TSORT(1P)