NAME

tsort - topologically sort symbols



SYNOPSIS

tsort [files ...]



DESCRIPTION

Tsort
topologically sorts the symbols in the named files.
If no files are specified, or the filename '-' is given,
tsort reads the standard input.

A symbol is considered any string of characters delimited
by blanks or tabs.

Each line of the input is assumed to be of the form



a b c ...



which states that
a
precedes
b, a
precedes
c,
and so on.
Note that there is nothing implied about the ordering of
b
and
c.
A line consisting of a single symbol simply "declares"
that symbol without specifying any ordering relations about it.
The output is a topologically sorted
list of symbols, one per line.


For example, suppose you have trouble getting up in the morning
because you can't quite remember what actions have to be
performed in which order.
However, you do know that the first action in the following
list precedes all others on the line:



set_alarm   turn_off_alarm
wake_up    get_out_of_bed    turn_off_alarm
set_alarm     wake_up



Using tsort to sort the above list would produce the following
set of actions for getting out of bed:



set_alarm
wake_up
turn_off_alarm
get_out_of_bed





DIAGNOSTICS

circular


The input specifies a graph that contains at least one cycle.


out of storage


The input is too large.
The size of tsort's buffer is determined by the MAXBUF
definition in the source code.




SEE ALSO

sort



AUTHORS

David Hanson and friends (U. of Arizona)