Transmission: set download speed from script

#!/bin/bash
USER=yourUserName
PASS=yourPassword
server=http://yourTransmissionHostIP
speed=$1
curlout=$(curl -u $USER:$PASS ${server}:9091/transmission/rpc 2>/dev/null)
regex='(X-Transmission-Session-Id\: )([^<]*)'
if [[ $curlout =~ $regex ]]; then
    sessionid=${BASH_REMATCH[2]}
else
    exit 1
fi
if [ $# -eq 0 ] ; then
	data='{"method": "session-set", "arguments": { "speed-limit-down-enabled" : false } }'
else
	data='{"method": "session-set", "arguments": { "speed-limit-down-enabled" : true, "speed-limit-down" :'
	data="$data ${speed} } }"
fi
curl -u $USER:$PASS ${server}:9091/transmission/rpc -d "$data" -H "X-Transmission-Session-Id: $sessionid"  > /dev/null 2>&1
]]>