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.\" 37.Dd April 1, 1994 38.Dt TSORT 1 39.Os 40.Sh NAME 41.Nm tsort 42.Nd topological sort of a directed graph 43.Sh SYNOPSIS 44.Nm tsort 45.Op Fl l 46.Op Ar file 47.Sh DESCRIPTION 48.Nm Tsort 49takes a list of pairs of node names representing directed arcs in 50a graph and prints the nodes in topological order on standard output. 51Input is taken from the named 52.Ar file , 53or from standard input if no file 54is given. 55.Pp 56Node names in the input are separated by white space and there must 57be an even number of node pairs. 58.Pp 59Presence of a node in a graph can be represented by an arc from the node 60to itself. 61This is useful when a node is not connected to any other nodes. 62.Pp 63If the graph contains a cycle (and therefore cannot be properly sorted), 64one of the arcs in the cycle is ignored and the sort continues. 65Cycles are reported on standard error. 66.Pp 67The options are as follows: 68.Bl -tag -width Ds 69.It Fl l 70Search for and display the longest cycle. 71Can take a very long time. 72.El 73.Sh SEE ALSO 74.Xr ar 1 75.Sh HISTORY 76A 77.Nm 78command appeared in 79.At v7 . 80This 81.Nm tsort 82command and manual page are derived from sources contributed to Berkeley by 83Michael Rendell of Memorial University of Newfoundland. 84