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.\" %sccs.include.redist.roff% 8.\" 9.\" @(#)tsort.1 8.3 (Berkeley) 04/01/94 10.\" 11.Dd 12.Dt TSORT 1 13.Os 14.Sh NAME 15.Nm tsort 16.Nd topological sort of a directed graph 17.Sh SYNOPSIS 18.Nm tsort 19.Op Fl l 20.Op Ar file 21.Sh DESCRIPTION 22.Nm Tsort 23takes a list of pairs of node names representing directed arcs in 24a graph and prints the nodes in topological order on standard output. 25Input is taken from the named 26.Ar file , 27or from standard input if no file 28is given. 29.Pp 30Node names in the input are separated by white space and there must 31be an even number of node pairs. 32.Pp 33Presence of a node in a graph can be represented by an arc from the node 34to itself. 35This is useful when a node is not connected to any other nodes. 36.Pp 37If the graph contains a cycle (and therefore cannot be properly sorted), 38one of the arcs in the cycle is ignored and the sort continues. 39Cycles are reported on standard error. 40.Pp 41The options are as follows: 42.Bl -tag -width Ds 43.It Fl l 44Search for and display the longest cycle. 45Can take a very long time. 46.El 47.Sh SEE ALSO 48.Xr ar 1 49.Sh HISTORY 50A 51.Nm 52command appeared in 53.At v7 . 54This 55.Nm tsort 56command and manual page are derived from sources contributed to Berkeley by 57Michael Rendell of Memorial University of Newfoundland. 58