misc_cmds/tsort/tsort.1

   1 .\"     $NetBSD: tsort.1,v 1.7 1997/10/20 01:09:53 lukem Exp $
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   7 .\" Michael Rendell of Memorial University of Newfoundland.
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  37 .\"     @(#)tsort.1     8.3 (Berkeley) 4/1/94
  38 .\"
  39 .Dd April 1, 1994
  40 .Dt TSORT 1
  41 .Os
  42 .Sh NAME
  43 .Nm tsort
  44 .Nd topological sort of a directed graph
  45 .Sh SYNOPSIS
  46 .Nm
  47 .Op Fl l
  48 .Op Fl q
  49 .Op Ar file
  50 .Sh DESCRIPTION
  51 .Nm
  52 takes a list of pairs of node names representing directed arcs in
  53 a graph and prints the nodes in topological order on standard output.
  54 Input is taken from the named
  55 .Ar file ,
  56 or from standard input if no file
  57 is given.
  58 .Pp
  59 Node names in the input are separated by white space and there must
  60 be an even number of node pairs.
  61 .Pp
  62 Presence of a node in a graph can be represented by an arc from the node
  63 to itself.
  64 This is useful when a node is not connected to any other nodes.
  65 .Pp
  66 If the graph contains a cycle (and therefore cannot be properly sorted),
  67 one of the arcs in the cycle is ignored and the sort continues.
  68 Cycles are reported on standard error.
  69 .Pp
  70 The options are as follows:
  71 .Bl -tag -width Ds
  72 .It Fl l
  73 Search for and display the longest cycle.
  74 Can take a very long time.
  75 .It Fl q
  76 Do not display informational messages about cycles.  This is primarily
  77 intended for building libraries, where optimal ordering is not critical,
  78 and cycles occur often.
  79 .El
  80 .Sh SEE ALSO
  81 .Xr ar 1
  82 .Sh HISTORY
  83 A
  84 .Nm
  85 command appeared in
  86 .At v7 .
  87 This
  88 .Nm
  89 command and manual page are derived from sources contributed to Berkeley by
  90 Michael Rendell of Memorial University of Newfoundland.