1.\" Copyright (c) 1990, 1993, 1994 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This manual is derived from one contributed to Berkeley by 5.\" Michael Rendell of Memorial University of Newfoundland. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)tsort.1 8.3 (Berkeley) 4/1/94 32.\" $FreeBSD$ 33.\" 34.Dd December 27, 2006 35.Dt TSORT 1 36.Os 37.Sh NAME 38.Nm tsort 39.Nd topological sort of a directed graph 40.Sh SYNOPSIS 41.Nm 42.Op Fl dlq 43.Op Ar file 44.Sh DESCRIPTION 45The 46.Nm 47utility takes a list of pairs of node names representing directed arcs in 48a graph and prints the nodes in topological order on standard output. 49Input is taken from the named 50.Ar file , 51or from standard input if no file 52is given. 53.Pp 54There must be an even number of nodes in the input. 55Node names specified on the same line should be white space separated. 56.Pp 57Presence of a node in a graph can be represented by an arc from the node 58to itself. 59This is useful when a node is not connected to any other nodes. 60.Pp 61If the graph contains a cycle (and therefore cannot be properly sorted), 62one of the arcs in the cycle is ignored and the sort continues. 63Cycles are reported on standard error. 64.Pp 65The options are as follows: 66.Bl -tag -width indent 67.It Fl d 68Turn on debugging. 69.It Fl l 70Search for and display the longest cycle. 71Can take a very long time. 72.It Fl q 73Do not display informational messages about cycles. 74This is primarily 75intended for building libraries, where optimal ordering is not critical, 76and cycles occur often. 77.El 78.Sh SEE ALSO 79.Xr ar 1 80.Sh HISTORY 81The 82.Nm 83command appeared in 84.At v7 . 85This 86.Nm 87command and manual page are derived from sources contributed to Berkeley by 88.An Michael Rendell 89of Memorial University of Newfoundland. 90.Sh BUGS 91The 92.Nm 93utility does not recognize multibyte characters. 94