Brian Kernighan, in a lecture at the University of Nottingham, described a problem on which this task is based.

Problem

You are given a a data file of thousands of lines; each of three `whitespace` separated fields: a date, a one word name and the magnitude of the event.

Example lines from the file would be lines like:

8/27/1883    Krakatoa            8.8
5/18/1980    MountStHelens       7.6
3/13/2009    CostaRica           5.1
Task

 Create a program or script invocation to find all the events with magnitude greater than 6
 Assuming an appropriate name e.g. "data.txt" for the file:
 Either: Show how your program is invoked to process a data file of that name.
 Or: Incorporate the file name into the program, (as it is assumed that the program is single use).


arg pop nip len dup
 
( [get nip]
  [drop drop "data.txt"]
) if
 
%f 
dup "r" fopen !f
$f 0 < ( [drop "Could not open '" print print "' for reading" print -1 end ] [drop] ) if
 
[dup split 3 get tonum 6 > ( [drop print nl] [drop drop] ) if]
[$f fgets dup -1 #] 
while
 
drop
$f fclose
 
"End " input