Question

In the Ruby string :

"${0} ${1} ${2:hello}"

is ${i} the ith argument in the command that called this particular file.

Tried searching the web for “Ruby ${0}” however the search engines don’t like non-alphanumeric characters.

Consulted a Ruby book which says #{…} will substitute the results of the code in the braces, however this does not mention ${…}, is this a special syntax to substitute argvalues into a string, thanks very much,

Joel

Answer 1

As mentioned above ${0} will do nothing special, $0 gives the name of the script, $1 gives the first match from a regular expression.

To interpolate a command line argument you’d normally do this:

puts "first argument = #{ARGV[0]}"

However, ARGV is also aliased as $* so you could also write

puts "first argument = #{$*[0]}"

Perhaps that’s where the confusion arose?