tsort(1)

NAME
     tsort - topological sort

SYNOPSIS
     tsort [file]

DESCRIPTION
     The tsort command produces on the standard output a totally ordered list
     of items consistent with a partial ordering of items mentioned in the
     input file.  If no file is specified, the standard input is understood.

     The input consists of pairs of items (nonempty strings) separated by
     blanks.  Pairs of different items indicate ordering.  Pairs of identical
     items indicate presence, but not ordering.

DIAGNOSTICS
     Odd data: there is an odd number of fields in the input file.