1.\" Copyright (c) 1990, 1993 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.\" %sccs.include.redist.roff% 7.\" 8.\" @(#)tsort.1 8.1 (Berkeley) 06/09/93 9.\" 10.Dd 11.Dt TSORT 1 12.Os 13.Sh NAME 14.Nm tsort 15.Nd topological sort of a directed graph 16.Sh SYNOPSIS 17.Nm tsort 18.Op Ar file 19.Sh DESCRIPTION 20.Nm Tsort 21takes a list of pairs of node names representing directed arcs in 22a graph and prints the nodes in topological order on standard output. 23Input is taken from the named 24.Ar file , 25or from standard input if no file 26is given. 27.Pp 28Node names in the input are separated by white space and there must be an 29even number of nodes. 30.Pp 31Presence of a node in a graph can be represented by an arc from the node 32to itself. 33This is useful when a node is not connected to any other nodes. 34.Pp 35If the graph contains a cycle (and therefore cannot be properly sorted), 36one of the arcs in the cycle is ignored and the sort continues. 37Cycles are reported on standard error. 38.Sh SEE ALSO 39.Xr ar 1 40.Sh HISTORY 41A 42.Nm 43command appeared in 44.At v7 . 45This 46.Nm tsort 47command and manual page are derived from sources contributed to Berkeley by 48Michael Rendell of Memorial University of Newfoundland. 49