tsort

Topological sort, perform a topological sort on the given FILE, or standard input if no input file is given or for a FILE of `-'.

SYNTAX
      tsort [OPTION] [FILE]

OPTIONS

--help
--version

`tsort' reads its input as pairs of strings, separated by blanks,
indicating a partial ordering.  The output is a total ordering that
corresponds to the given partial ordering.

   For example

     tsort <<EOF
     a b c
     d
     e f
     b c d e
     EOF

will produce the output

     a
     b
     c
     d
     e
     f

`tsort' will detect cycles in the input and writes the first cycle
encountered to standard error.

"There is always room at the top" - Daniel Webster

Related commands:

sort - Sort text files