This works quite nicely - just wondered if there are any improvements to shorten it ?
if (ARGV.nil?) then
# Do something with the input here, for example:
input.each_line do |line|
You can eliminate the first five lines entirely.
$<: An object that provides access to the concatenation of the contents of all the files given as command-line arguments or $stdin (in the case where there are no arguments). $< supports methods similar to a File object: binmode, close, closed?, each, each_byte, each_line, eof, eof?, file, filename, fileno, getc, gets, lineno, lineno=, path, pos, pos=, read, readchar, readline, readlines, rewind, seek, skip, tell, to_a, to_i, to_io, to_s, along with the methods in Enumerable. The method file returns a File object for the file currently being read. This may change as $< reads through the files on the command line. [r/o]
Kernel.gets is shorthand for $<.gets, so:
while s = gets puts s end