tsort (1p) - Linux Man Pages
tsort: topological sort
PROLOGThis 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
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>s. Pairs of different items indicate ordering. Pairs of identical items indicate presence, but not ordering.
The following operand shall be supported:
A pathname of a text file to order. If no file operand is given,
the standard input shall be used.
The following environment variables shall affect the execution of tsort:
- 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 Variables for the precedence of internationalization variables used to determine the values of locale categories.)
- If set to a non-empty string value, override the values of all the other internationalization variables.
- 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).
- Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.
Determine the location of message catalogs for the processing of LC_MESSAGES
The following exit values shall be returned:
- Successful completion.
- An error occurred.
CONSEQUENCES OF ERRORS
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
COPYRIGHTPortions 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 .