In order to solve a programming assignment (send a “TEST” to an UDP service and readout the result [beeing "success"]) i looked into socket programming with the BASH command shell.

Here is the code:

# configurationHOST="127.0.0.1"PORT="1337"# define functionssocksend (){	SENDME="$1"	echo "sending: $SENDME"	echo -ne "$SENDME" >&5 &}sockread (){	LENGTH="$1"	RETURN=`dd bs=$1 count=1 <&5 2> /dev/null`}echo "trying to open socket"# try to connectif ! exec 5<> /dev/udp/$HOST/$PORT; then  echo "`basename $0`: unable to connect to $HOST:$PORT"  exit 1fiecho "socket is open"# send requestsocksend "TEST"# read 7 bytes for "success"sockread 7echo "RETURN: $RETURN"

The procedure is fairly easy:

- create a filedescriptor (using number 5 because 0,1,2 are for system stdin/stdout/stderr, so i am on the safe side) and link it to the special device /dev/udp (/dev/tcp for tcp connections). - read/write to the fd

Attention: your bash must be compiled with this feature, otherwise there wont be any /dev/udp or /dev/tcp devices.

My post should answer the question posted here:

Also, i stumbled across those pages which where quite helpful for getting started: