tsort -- topological sort of a directed graph
tsort [-dlq] [file]
The tsort utility 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 given.
Node names in the input are separated by white space and there must be an
even number of nodes.
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 Turn on debugging.
-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.
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.
FreeBSD 5.2.1 April 1, 1994 FreeBSD 5.2.1 [ Back ]