E. Scripts: Building New Tools and Putting them on the Web
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Once we figure out a pipeline to answer a questions we want to save
that pipeline so we can reuse it.  We do that by putting the pipeline
in a script:

   #!/bin/sh
   # train-times for a station and direction
   grep "stn=brockton" sched | grep "dir=i" | cut -d";" -f4

But that only works for inbound through brockton.  To make it more
general, we would like to have a tool that works like

   train-times salem o

To do that, we put in parameters for the things to vary:

   #!/bin/sh
   # train-times for a station and direction
   # usage: train-times station-name {i|o}
   grep "stn=$1" sched | grep "dir=$2" | cut -d";" -f4

TODO: modify this so it also allows you to specify m-f, sa, or su