NAME

tsort — topological sort

SYNOPSIS

tsort [file]

DESCRIPTION

Tsort reads a file consisting of pairs of items (non-empty strings) separated by blanks, and generates a completely ordered list of items consistent with a partial ordering of the items mentioned in the input file.  If the input file is not specified, tsort uses the standard input. 

The input file consists of pairs of items.  Pairs of different items indicate ordering.  Pairs of identical items indicate existence but not ordering. 

SEE ALSO

lorder(1)

MESSAGES

cannot open filename
Tsort was unable to open the file specified on the command line.  Check the spelling, or make sure that you have permission to read that file. 

odd data
There is an odd number of fields in the input file.  There should be two entries on every line.

too many items
Tsort cannot handle the number of items in the input file. 

cycle in data
The partial ordering of the fields in the input file form a cyclical dependency on each other.

program error
Tsort has arrived at a “cannot happen” situation internally — consult your local wizard. 

7th Edition  —  Revision 1.3 of UniSoft UNIX — 12/15/82