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Turns Ruby into a versatile command line utility
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LICENSE Create LICENSE Aug 16, 2018


With 9 lines of Ruby replace most of the command line tools that you use to process text inside of the terminal.

Here's the code

#!/usr/bin/env ruby
File.join(Dir.home, '.rbrc').tap { |f| load f if File.exists?(f) }

def execute(_, code)
  puts _.instance_eval(&code)
rescue Errno::EPIPE

single_line = ARGV.delete('-l')
code = eval(" { #{ARGV.join(' ')} }")
single_line ? STDIN.each { |l| execute(l.chomp, code) } : execute(STDIN.each_line, code)

Clone this repo and copy the rb file to somewhere in your path (or just copy and paste the above).

With this you can use ruby as a command line utility much more ergonomically than invoking it the standard way.

There's only one switch -l which runs your code on each line separately. Otherwise you get an Enumerator that returns the lines of stdin. It's instance_evaled so some methods need self to work, eg. self[-1]


Just paste this line into your terminal to install rb:

sudo curl -o /usr/local/bin/rb && sudo chmod +x /usr/local/bin/rb


Extract docker images from running containers
> docker ps | rb drop 1 | rb -l split[1]

# ubuntu
# postgres
Display how much time ago containers have exited
> docker ps -a | rb grep /Exited/ | rb -l 'split.last.ljust(20) + " => " + split(/ {2,}/)[-2]'

# angry_hamilton      => Exited (0) 18 hours ago
# dreamy_lamport      => Exited (0) 3 days ago
# prickly_hypatia     => Exited (0) 2 weeks ago
Sort df -h output by Use%
> df -h | rb 'drop(1).sort_by { |l| l.split[-2].to_f }'

# udev                         3,9G     0  3,9G   0% /dev
# tmpfs                        3,9G     0  3,9G   0% /sys/fs/cgroup
# /dev/sda1                    511M  3,4M  508M   1% /boot/efi
# /dev/sda2                    237M   85M  140M  38% /boot

# or leave the header if you want
> df -h | rb '[first].concat drop(1).sort_by { |l| l.split[-2].to_f }'

# Filesystem                   Size  Used Avail Use% Mounted on
# udev                         3,9G     0  3,9G   0% /dev
# tmpfs                        3,9G     0  3,9G   0% /sys/fs/cgroup
# /dev/sda1                    511M  3,4M  508M   1% /boot/efi
# /dev/sda2                    237M   85M  140M  38% /boot
Count files by their extension
> find . -type f | rb 'group_by(&File.method(:extname)).map { |ext, o| "#{ext.chomp}: #{o.size}" }'

# : 3
# .rb: 19
# .md: 1
This problem
ls | rb 'group_by { |x| x[/\d+/] }.select { |_, y| }.keys'

Extending rb

The ~/.rbrc file is loaded if it's available. Anything defined in there will be available inside rb scripts.

# ~/.rbrc

class String
  def black; "\033[30m#{self}\033[0m" end
  def red;   "\033[31m#{self}\033[0m" end
> ls | rb
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