The send/receive commands support multi-part bulk dumps, with the ability to save multiple sysex messages into a single file (which is required for e.g. XG bulk dumps, which consist of hundreds of separate SysEx messages). When sending multi-part dumps, there's an adjustable delay between the single sysex messages to prevent buffer overflows on the receiving machine.

To make usage more comfortable, MIDI source/destination ports can be given as system-internal numeric IDs, e.g. instead of
  syxsend /dev/midi/serial/MU90/MU90A file.syx
you can use
  syxsend 3 file.syx.
The ID numbers for the MIDI ports can be displayed with the included midiports command.