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. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)tsort.1 8.3 (Berkeley) 4/1/94 36.\" $FreeBSD$ 37.\" 38.Dd December 27, 2006 39.Dt TSORT 1 40.Os 41.Sh NAME 42.Nm tsort 43.Nd topological sort of a directed graph 44.Sh SYNOPSIS 45.Nm 46.Op Fl dlq 47.Op Ar file 48.Sh DESCRIPTION 49The 50.Nm 51utility takes a list of pairs of node names representing directed arcs in 52a graph and prints the nodes in topological order on standard output. 53Input is taken from the named 54.Ar file , 55or from standard input if no file 56is given. 57.Pp 58There must be an even number of nodes in the input. 59Node names specified on the same line should be white space separated. 60.Pp 61Presence of a node in a graph can be represented by an arc from the node 62to itself. 63This is useful when a node is not connected to any other nodes. 64.Pp 65If the graph contains a cycle (and therefore cannot be properly sorted), 66one of the arcs in the cycle is ignored and the sort continues. 67Cycles are reported on standard error. 68.Pp 69The options are as follows: 70.Bl -tag -width indent 71.It Fl d 72Turn on debugging. 73.It Fl l 74Search for and display the longest cycle. 75Can take a very long time. 76.It Fl q 77Do not display informational messages about cycles. 78This is primarily 79intended for building libraries, where optimal ordering is not critical, 80and cycles occur often. 81.El 82.Sh SEE ALSO 83.Xr ar 1 84.Sh HISTORY 85The 86.Nm 87command appeared in 88.At v7 . 89This 90.Nm 91command and manual page are derived from sources contributed to Berkeley by 92.An Michael Rendell 93of Memorial University of Newfoundland. 94.Sh BUGS 95The 96.Nm 97utility does not recognize multibyte characters. 98