out.rb

eval(s="tobf=->s{s.chars.map{|c|%([-])+?+*c.ord+?.}.join};a,b=[\"package main;import \\\"fmt\\\";func main(){fmt.Println(\\\"<?php echo(\\\\\\\"print(\\\\\\\\\\\\\\\"console.log(\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\"#include<stdio.h>\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\nint main(){puts(\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\"\", \"\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\");}\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\")\\\\\\\\\\\\\\\")\\\\\\\");\\\")}\"];c=%[eval(s=]+s.inspect+?);5.times{c=c.inspect[1...-1]};puts tobf[a+c+b]")

relay_generator.rb

code = '%s'
code = %(#include<stdio.h>\nint main(){puts(#{code.inspect});})
code = %(console.log(#{code.inspect}))
code = %(print(#{code.inspect}))
code = %(<?php echo(#{code.inspect});)
code = %(package main;import "fmt";func main(){fmt.Println(#{code.inspect})})


a,b = code.split('%s')

numlangs = 5
c=(
  'eval(s='+
    (
      %(tobf=->s{s.chars.map{|c|%([-])+?+*c.ord+?.}.join};)+
      %(a,b=#{[a,b].inspect};c=%[eval(s=]+s.inspect+?);#{numlangs}.times{c=c.inspect[1...-1]};puts tobf[a+c+b])
    ).inspect+
  ')'
)
numlangs.times{ c=c.inspect[1...-1]}
out = a + c + b

# puts a
# puts b
# exit
def bfeval code
  array = []
  idx = 0
  output = []
  eval code.scan(/[\[\].,><+-]/).map(&{
    '[' => 'while array[idx].to_i != 0',
    ']' => 'end',
    '.' => 'output<<array[idx].to_i.chr',
    ',' => 'array[idx] = getc.ord',
    '+' => 'array[idx] = array[idx].to_i + 1',
    '-' => 'array[idx] = array[idx].to_i - 1',
    '>' => 'idx+=1',
    '<' => 'idx-=1'
  }).join(';')
  output.join
end

puts out
File.write('out.go', out)
`go run out.go > out.php`
`php out.php > out.py`
`python out.py > out.js`
`node out.js > out.c`
`cc out.c && ./a.out > out.rb`
`ruby out.rb > out.bf`
out2 = bfeval File.read('out.bf')
puts out==out2
puts out2