Updated: 2021/Apr/14

TSORT(1)                    General Commands Manual                   TSORT(1)

     tsort - topological sort of a directed graph

     tsort [-d] [-l] [-q] [-r] [file]

     tsort takes a list of pairs of node names representing directed arcs in a
     graph and prints the nodes in topological order on standard output.
     Input is taken from the named file, or from standard input if no file is

     Node names in the input are separated by white space and there must be an
     even number of node names.

     Presence of a node in a graph can be represented by an arc from the node
     to itself.  This is useful when a node is not connected to any other

     If the graph contains a cycle (and therefore cannot be properly sorted),
     one of the arcs in the cycle is ignored and the sort continues.  Cycles
     are reported on standard error.

     The options are as follows:

     -d      Print debugging information.

     -l      Search for and display the longest cycle.  Can take a very long

     -q      Do not display informational messages about cycles.  This is
             primarily intended for building libraries, where optimal ordering
             is not critical, and cycles occur often.

     -r      Reverse the sort.


     A tsort command appeared in Version 7 AT&T UNIX.  This tsort command and
     manual page are derived from sources contributed to Berkeley by Michael
     Rendell of Memorial University of Newfoundland.

NetBSD 9.99                     August 12, 2020                    NetBSD 9.99