What are the reserved words BEGIN or END used for in Ruby?

Question

This is a very hard to find word because in most cases they are not sensitive during a search. The best I could find outside of documentation is a test in IRB.

Answer 1

the BEGIN/END is really handy when using the -e option to process a stream. For example, to total a file of numbers:

cat < numbers
1
5 
10
20
EOF

cat numbers | ruby -ane 'BEGIN { $t=0}; END {puts $t}; $t += $_.to_i'

note how the BEGIN zeros out the global, and the END prints the result.