1.\" $NetBSD: tsort.1,v 1.10 2003/08/07 11:16:50 agc 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. Neither the name of the University nor the names of its contributors 18.\" may be used to endorse or promote products derived from this software 19.\" without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31.\" SUCH DAMAGE. 32.\" 33.\" @(#)tsort.1 8.3 (Berkeley) 4/1/94 34.\" 35.Dd April 1, 1994 36.Dt TSORT 1 37.Os 38.Sh NAME 39.Nm tsort 40.Nd topological sort of a directed graph 41.Sh SYNOPSIS 42.Nm 43.Op Fl l 44.Op Fl q 45.Op Ar file 46.Sh DESCRIPTION 47.Nm 48takes a list of pairs of node names representing directed arcs in 49a graph and prints the nodes in topological order on standard output. 50Input is taken from the named 51.Ar file , 52or from standard input if no file 53is given. 54.Pp 55Node names in the input are separated by white space and there must 56be an even number of node names. 57.Pp 58Presence of a node in a graph can be represented by an arc from the node 59to itself. 60This is useful when a node is not connected to any other nodes. 61.Pp 62If the graph contains a cycle (and therefore cannot be properly sorted), 63one of the arcs in the cycle is ignored and the sort continues. 64Cycles are reported on standard error. 65.Pp 66The options are as follows: 67.Bl -tag -width Ds 68.It Fl l 69Search for and display the longest cycle. 70Can take a very long time. 71.It Fl q 72Do not display informational messages about cycles. 73This is primarily 74intended for building libraries, where optimal ordering is not critical, 75and cycles occur often. 76.El 77.Sh SEE ALSO 78.Xr ar 1 79.Sh HISTORY 80A 81.Nm 82command appeared in 83.At v7 . 84This 85.Nm 86command and manual page are derived from sources contributed to Berkeley by 87Michael Rendell of Memorial University of Newfoundland. 88