So, this same command I'm trying to send from inside application. Code is this :
B4X:
Dim shl As Shell
shl.Initialize("shl", "echo", Array As String("some text to be printed", ">>", "/dev/usb/lp0"))
shl.WorkingDirectory = File.DirApp
shl.Run(-1)
Thank you for your answer and for the link.
Same thing ... unfortunately not working also like that.
For the record, I have done it another way ... I do create bash script from my application, give bash script privilege to run, and execute it with shell run command. To script I can send parameters, so basically quite flexible solution. Not most elegant one, but works.