This is how i do it from Windows (rar.exe) the linux port should be the same:
dir \temp /s|"\Program Files\WinRAR"\rar a -siInsidefile.txt -v1024b -ag_MMMDDYYYY-HHMM archive
this gives me : archive_May312016-0945.part1.rar archive_May312016-0945.part2.rar archive_May312016-0945.part3 ... etc
wich contains: insidefile.txt
of 1024 bytes each
with the text file holding the contents of the redirection of my dir command.