Create a simple histogram or bar-chart in bash

The following script accepts (via stdin) input like this:

foo 10
bar 21
xyzzy 12

and generates (to stdout) a bar-chart like this:

+-------+----+
|   foo | 10 | ##########
|   bar | 21 | #####################
| xyzzy | 12 | ############
+-------+----+

where the width of the headings (category and count) is automatically determined by the input values and the width of the bar chart (the number of # characters) is automatically scaled to fit within the current terminal width.

It also demonstrates a few intermediate level awk features such as passing variables (via the -v parameter) and variable-width printf statements (via %*s).