TSORT(1) BSD General Commands Manual TSORT(1)NAMEtsort — topological sort of a directed graph
SYNOPSIStsort [-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.
There must be an even number of nodes in the input. Node names specified
on the same line should be white space separated.
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 pri‐
marily intended for building libraries, where optimal ordering is
not critical, and cycles occur often.
The 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.
The tsort utility does not recognize multibyte characters.
BSD December 27, 2006 BSD