ruby - IO.popen not working lame stdin and stdout encoding

Question

I've been working with pipes and `IO.popen` specifically in Ruby and have come across a problem that I can't figure out. I am trying to write binary data from the `flac` process to the `lame` process into a file. The code structure I am using is below. ``` # file paths file = Pathname.new('example.flac').realpath dest = Pathname.new('example.mp3') # execute the process and return the IO object wav = IO.popen("flac --decode --stdout \"#{file}\"", 'rb') lame = IO.popen("lame -V0 --vbr-new - -", 'r+b') # write output from wav to the lame IO object lame << wav.read # close pipe for writing (should indicate to the # process that input for stdin is finished). lame.close_write # open up destiniation file and write from lame stdout dest.open('wb'){|out| out << lame.read } # close all pipes wav.close lame.close ``` However, it doesn't work. After `flac` has run, the script hangs and `lame` remains idle (no processor usage at all). No errors or exceptions occur. I am using cygwin on Windows 7,…

Accepted Answer

Did you try the pipe `|` character? Tested this on windows with ruby installer

```
require 'open3'

command = 'dir /B | sort /R'  # a windows example command
Open3.popen3(command) {|stdin, stdout, stderr, wait_thr|
  pid = wait_thr.pid
  puts stdout.read  #<a list of files in cwd in reverse order>
}
```

Other ways: Ruby pipes: How do I tie the output of two subprocesses together?

EDIT: using `IO::pipe`

```
require 'open3'

command1 = 'dir /B'
command2 = 'sort /R'

reader,writer = IO.pipe
Open3.popen3(command1) {|stdin, stdout, stderr, wait_thr|
  writer.write stdout.read
}
writer.close

stdout, stderr, status = Open3.capture3(command2, :stdin_data => reader.read)
reader.close

puts "status: #{status}"   #pid and exit code
puts "stderr: #{stderr}"   #use this to debug command2 errors
puts stdout
```

Embedding the two also appears to work, yet, as the blog you referred to said, one must wait for the first command to finish (not real-time -- test with a ping command)

```
stdout2 = ''
Open3.popen3(command1) {|stdin, stdout, stderr, wait_thr|
  stdout2, stderr2, status2 = Open3.capture3(command2, :stdin_data => stdout.read)
}
puts stdout2
```

ruby - IO.popen not working lame stdin and stdout encoding

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