script.rb:
puts 'hello'
puts 'foo'
main.rb:
puts `jruby script.rb` # receive the expected result
The question:
How can the same be achieved with reading the "script" before execution?
main.rb:
code=File.open('script.rb', 'r').read.gsub('"', '\"')
# puts `jruby -e '#{code}'` # Does not work for relatively big files;
Windows and unicode are the reasons of this question;
Please note that `jruby script.rb' creates a new process which is essential.
Store the modified script in a Tempfile and run that instead of passing the whole contents as an eval argument:
require 'tempfile'
code = IO.read('script.rb').gsub('"', '\"')
begin
tempfile = Tempfile.new 'mytempfile'
f.write code
f.close
puts `jruby '#{f.path}'`
ensure
f.close
f.unlink
end
The reason you’re likely getting an error is either a lack of proper escaping or a limit on the maximum argument length in the shell.
Also, beware that in your original implementation you never close the original file. I’ve fixed that by instead using IO.read.
jruby IO.read('script.rb') ` (read and exec)
In the command line, using
$ getconf ARG_MAX
will give the upper limit on how many bytes can be used for the command line argument and environment variables.
@Andrew Marshall's answer is better, but suppose you don't want to use a temp file, and assuming we can use fork in JRuby,
require 'ffi'
module Exec
extend FFI::Library
ffi_lib FFI::Platform::LIBC
attach_function :fork, [], :int
end
code = IO.read('script.rb')
pid = Exec.fork
if 0 == pid
eval code
exit 0
else
Process.waitpid pid
end
jruby main.rb