#!/bin/bash
# usage: rigol-snapshot <filename_with_wellknown_imagefile_extension>
#        e.g.: rigol-snapshot pics/test.jpg
#   fetches a bmp formatted screenshot picture from Rigol DS1000 series, via ethernet
# TODO: proper handling of broken connection to Rigol, check netcat / read return code

: ${RIGOL_IP:=192.168.4.52}   # adapt to your local situation, I used fixed DHCP IP for rigol in my router

echo ':disp:data?' | netcat -w 1 $RIGOL_IP 5555\
 | (shopt -s extglob;
    sleep 0.1
    read -N 1 -t 0.1 magichash;
    read -N 1 -t 0.1 lenofnum; 
    read -N $lenofnum -t 0.1 numofbytes; 
    #echo -e "1.magic: $magichash; 2.len_hdr: $lenofnum: \"${numofbytes}\"=bytes-netto-data\nreading..." >&2
    head -c ${numofbytes##*(0)} ; 
    # seems either this cleanup of remaining bytes, or the above sleep 0.1, is needed to avoid every ~2nd run fail
    echo -e "cleanup: \n`od -x`" >&2
   )\
 | convert bmp:- $1
rc=$?
echo "returncode: $rc" >&2
exit $rc




#legacy
#echo ':disp:data?' | netcat 192.168.4.52 5555 | dd bs=1M iflag=skip_bytes skip=11 of=$1
#echo ':disp:data?' | netcat 192.168.4.52 5555 | dd bs=1M iflag=skip_bytes skip=11 | convert bmp:- $1
#echo ':disp:data?' | netcat 192.168.4.52 5555 | head -c -3 | dd bs=1M iflag=skip_bytes skip=11 |  convert bmp:- $1