Show HN: Rb – Turns Ruby into a command line utility
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Re: Show HN: Rb – Turns Ruby into a command line utility
#2I have no idea what this is doing, but it sure looks interesting.
Re: Show HN: Rb – Turns Ruby into a command line utility
#3I have no idea what this is doing, but it sure looks interesting.
It's using Ruby to replace Awk, the way Perl once tried to.
Re: Show HN: Rb – Turns Ruby into a command line utility
#4I have no idea what this is doing, but it sure looks interesting.
It's feeding stdin to ruby code you specify on the command line, either as an array of lines, or repeated strings. So in:
docker ps | rb drop 1 | rb -l split[1]
docker ps | rb drop(1) | rb -l split()[1]Re: Show HN: Rb – Turns Ruby into a command line utility
#5What does this have over the default ruby?
cat your-file.txt | ruby -ne '$_.your_ruby_stuff'
Just syntactic sugar? (it does look cleaner!)
Re: Show HN: Rb – Turns Ruby into a command line utility
#6I have no idea what this is doing, but it sure looks interesting.
It's feeding stdin to ruby code you specify on the command line, either as an array of lines, or repeated strings. So in: docker ps | rb drop 1 | rb -l split[1] The output of docker ps is passed as an array of lines to ruby, and the first line is dropped, and then that output is fed to ruby again, but line by line, so each line is split (which defaults to split on whitespace), and returns the second element. With par…
So drop is just a Ruby function? This is a great idea, seems like a good application of Ruby's syntax.
Re: Show HN: Rb – Turns Ruby into a command line utility
#7Command line tools in 10 lines of ruby (using this script):
docker ps | rb drop 1 | rb -l split[1]
docker ps -a | rb grep /Exited/ | rb -l 'split.last.ljust(20) + " => " + split(/ {2,}/)[-2]'
df -h | rb 'drop(1).sort_by { |l| l.split[-2].to_f }'
docker ps | ruby -lane 'next if $. == 1; print $F[1]
docker ps -a | ruby -lne 'print $1 if /(Exited .*? ago)/'
df | ruby -lane 'BEGIN { lines = [] }; lines.push [$F[4].to_i, $_] if $. > 0; END { lines.sort { |a,b|b[0] a[0] }.each{|k| print k[1] } }
Re: Show HN: Rb – Turns Ruby into a command line utility
#8What does this have over the default ruby? cat your-file.txt | ruby -ne '$_.your_ruby_stuff' Just syntactic sugar? (it does look cleaner!)
My guess is that the author was unaware of those flags. matz's idea that Ruby be a worthy successor to Perl was sort of crushed by Java weenies when the Pickaxe book came out.
I know this is ancient history.
Re: Show HN: Rb – Turns Ruby into a command line utility
#9Interesting, 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
printf 'hello\nworld\nhello\n' | rb uniq
printf '1\n2\n3\n' | rb 'map(&:to_i).sum'