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 April 1, 1994 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 d 47.Op Fl l 48.Op Fl q 49.Op Ar file 50.Sh DESCRIPTION 51The 52.Nm 53utility takes a list of pairs of node names representing directed arcs in 54a graph and prints the nodes in topological order on standard output. 55Input is taken from the named 56.Ar file , 57or from standard input if no file 58is given. 59.Pp 60Node names in the input are separated by white space and there must 61be an even number of nodes. 62.Pp 63Presence of a node in a graph can be represented by an arc from the node 64to itself. 65This is useful when a node is not connected to any other nodes. 66.Pp 67If the graph contains a cycle (and therefore cannot be properly sorted), 68one of the arcs in the cycle is ignored and the sort continues. 69Cycles are reported on standard error. 70.Pp 71The options are as follows: 72.Bl -tag -width Ds 73.It Fl d 74Turn on debugging. 75.It Fl l 76Search for and display the longest cycle. 77Can take a very long time. 78.It Fl q 79Do not display informational messages about cycles. This is primarily 80intended for building libraries, where optimal ordering is not critical, 81and cycles occur often. 82.El 83.Sh SEE ALSO 84.Xr ar 1 85.Sh HISTORY 86A 87.Nm 88command appeared in 89.At v7 . 90This 91.Nm 92command and manual page are derived from sources contributed to Berkeley by 93Michael Rendell of Memorial University of Newfoundland. 94