Comment by Ajedi32 | Hacker News Reader

Comment by Ajedi32 | Hacker News Reader

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Interesting, so it's reading text from STDIN into an Array, then executing its arguments as Ruby code in the context of that Array (or if you pass -l, in the context of each line individually). So all the standard methods on the [Array][1] (or [String][2]) class become accessible as top-level methods.

A few examples:

Capitalizing a line:

   echo hello world | rb -l capitalize

Printing only unique lines:

    printf 'hello\nworld\nhello\n' | rb uniq

Computing the sum of numbers in a table:

   printf '1\n2\n3\n' | rb 'map(&:to_i).sum'

Personally I think it's a really cool idea.

[1]: https://ruby-doc.org/core/Array.html

[2]: https://ruby-doc.org/core/String.html

    echo hello world | ruby -pe '$_.capitalize!'

    printf 'hello\nworld\nhello\n' | ruby -le 'puts STDIN.to_a.uniq

    ps | ruby -lane 'BEGIN { b = 0 }; b += $F[0].to_i; END { print "sum of PIDs: #{b}" }

select whatever column you want, to sum up.

Really what Ruby needs is a flag that adds some capabilities to NilClass, so that these BEGIN blocks aren't needed.

If this was an attempt at showing this tool is unnecessary, you just did the opposite.

Each of your examples use different flags, inputs and print methods. The last is particularly good at proving the point!

Each of those examples is doing different things. This rb script locks you into two of the options.

> Really what Ruby needs is a flag that adds some capabilities to NilClass, so that these BEGIN blocks aren't needed.

Does it, though?

  ps | ruby -le 'b = $<.reduce(0) {|s, l| s + l.split(0).to_i}; print "sum of PIDs: #{b}"'

or:

  ps | ruby -lane 'b = (b || 0) + $F[0].to_i; END { print "sum of PIDs: #{b}" }'

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