1.\" $NetBSD: tsort.1,v 1.8 2000/11/08 00:56:26 wiz Exp $ 2.\" 3.\" Copyright (c) 1990, 1993, 1994 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This manual is derived from one contributed to Berkeley by 7.\" Michael Rendell of Memorial University of Newfoundland. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the University of 20.\" California, Berkeley and its contributors. 21.\" 4. Neither the name of the University nor the names of its contributors 22.\" may be used to endorse or promote products derived from this software 23.\" without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35.\" SUCH DAMAGE. 36.\" 37.\" @(#)tsort.1 8.3 (Berkeley) 4/1/94 38.\" 39.Dd April 1, 1994 40.Dt TSORT 1 41.Os 42.Sh NAME 43.Nm tsort 44.Nd topological sort of a directed graph 45.Sh SYNOPSIS 46.Nm 47.Op Fl l 48.Op Fl q 49.Op Ar file 50.Sh DESCRIPTION 51.Nm 52takes a list of pairs of node names representing directed arcs in 53a graph and prints the nodes in topological order on standard output. 54Input is taken from the named 55.Ar file , 56or from standard input if no file 57is given. 58.Pp 59Node names in the input are separated by white space and there must 60be an even number of node names. 61.Pp 62Presence of a node in a graph can be represented by an arc from the node 63to itself. 64This is useful when a node is not connected to any other nodes. 65.Pp 66If the graph contains a cycle (and therefore cannot be properly sorted), 67one of the arcs in the cycle is ignored and the sort continues. 68Cycles are reported on standard error. 69.Pp 70The options are as follows: 71.Bl -tag -width Ds 72.It Fl l 73Search for and display the longest cycle. 74Can take a very long time. 75.It Fl q 76Do not display informational messages about cycles. This is primarily 77intended for building libraries, where optimal ordering is not critical, 78and cycles occur often. 79.El 80.Sh SEE ALSO 81.Xr ar 1 82.Sh HISTORY 83A 84.Nm 85command appeared in 86.At v7 . 87This 88.Nm 89command and manual page are derived from sources contributed to Berkeley by 90Michael Rendell of Memorial University of Newfoundland. 91