Cannot Run PacketTrace on Nano Version
Initially, I thought it was because the file system is mounted RO, but then I saw that the packetcapture.cap file is created, but always remains as a zero length file.
But, I still think the RO is part of the puzzle, because if I manually enter the command, and write the file to the /var/tmp directory, it works correctly. However, I could not reproduce the zero length file artifact.
BTW The instructions, and default value, for captured Packet Length are incorrect. The correct value should be 1514, or MTU Size + 14, because the capture includes the 14 byte Ethernet header.
This was noticed and fixed shortly after the 1.2.3 release, but since 1.2.x likely won't see any more releases, you can apply the fix manually: