cannot get serial_echo example to work

[john.k...@toptal.com]

For the life of me, I cannot get any output from the serial port at all. I don't really care about input - just want output, for debugging purposes. 

I'm on Ubuntu 14.04

Output of sudo stty -F /dev/ttyS0 

speed 9600 baud; line = 0;

intr = <undef>; quit = <undef>; erase = <undef>; kill = <undef>; eof = <undef>; start = <undef>;

stop = <undef>; susp = <undef>; rprnt = <undef>; werase = <undef>; lnext = <undef>; flush = <undef>;

min = 1; time = 1;

Using moserial, connected at 9600 baud

my build script: 

make clean 

make 

sudo make flash -j4 ESPPORT=/dev/ttyUSB0

I've tried other variations of baud and other serial port settings, nothing has worked. I don't get any errors, just no output at all. Not junk output, just no output at all. 

I run Windows & Arduino on the same machine, with the same ESP8266 chip, and get serial output at 9600 baud.  

Any suggestions would be super welcome. I've spent more time on this issue than would have been practical to expect. 

Thanks, 

John