Help with script issue involving serial device

[Dave Stevens]

I have a IOT device that communicates with my Mint  computer using a
UART as a level shifter, so 3.3V at the device becomes 5V at the USB
plug and socket. dmesg correctly shows the cp210x converter attached to
/dev/tty/USB0. I then copy incoming data from the device to a file
using cp and get meaningful data. The script looks like this

filename=$(date +%F%T)
touch $filename
cp dev/tty/USB0 $filename

The filename correctly reflects the  file creation date and time, this
is the intended effect.

When I first ran the script I got occasional  errors and I traced it
down to inadequate initialization of the serial port on my part. I
found I could run this commend to get reliable operation:

stty raw -R /dev/ttyUSB0 9600 cs8 -cstopb -parenb -ixon -ixoff

so the sequence was, run stty then  the three line script and all is
good.  The difficulty arose as soon as I inserted the stty command into
the script as the new line 1. Then the script fails to run. If I back
up to running the stty command standalone first then the three liner
works with no problems.

Can anyone see why this is? Not a dealbreaker but irritating.

Thanks,

Dave


-- 
Sometimes I wonder whether the world is being run by 
smart people who are putting us on or by imbeciles who 
really believe it.

Mark Twain