There is currently no way that I can see to set a Zabbix Trapper item (Type Text) to a multi-line text value.
This could be very useful for (for example) storing text log messages into zabbix items for processing.
I have created a patch for zabbix_sender that allows the individual item data to be read from standard-in when the host and key are specified on the command line.
The size of the text item read from stdin is currently limited to 64KB (The remainder is truncated.)
Cat LogItem.txt | zabbix_sender -z 127.0.0.1 -s TestHost -k TestItem -O