TSORT(1P) POSIX Programmer's Manual TSORT(1P)PROLOG
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implementation of this interface may differ (consult the corresponding
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NAMEtsort — topological sort
SYNOPSIStsort [file]
DESCRIPTION
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
None.
OPERANDS
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
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
The input file shall be a text file.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of
tsort:
LANG Provide a default value for the internationalization vari‐
ables that are unset or null. (See the Base Definitions vol‐
ume of POSIX.1‐2008, 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_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
Default.
STDOUT
The standard output shall be a text file consisting of the order list
produced from the partially ordered input.
STDERR
The standard error shall be used only for diagnostic messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
CONSEQUENCES OF ERRORS
Default.
The following sections are informative.
APPLICATION USAGE
The LC_COLLATE variable need not affect the actions of tsort. The out‐
put ordering is not lexicographic, but depends on the pairs of items
given as input.
EXAMPLES
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
None.
FUTURE DIRECTIONS
None.
SEE ALSO
The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
Variables
COPYRIGHT
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 Electri‐
cal 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.ker‐
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 TSORT(1P)
