J1939SPY(1)

💖 J1939SPY(1) 💖

okay bestie, welcome to section 1 of the manual — "User Commands" — and yes, we're the main character of executable programs today. This is j1939spy, and she is serving 2023.03-1build1 energy. Let's get into it. ✨

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🌸 NAME 🌸

j1939spy — literally the manual page for j1939spy version 2023.03-1build1. that's it, that's the name section, she's a simple girl. 🎀

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🦋 SYNOPSIS 🦋

j1939spy [OPTION...] [[IFACE:][NAME|SA][,PGN]]

yeah okay so you got your options, then optionally an interface, then optionally a name or a source address, then optionally a comma and a PGN. the whole back half is optional, she's flexible like that 💅

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🌈 DESCRIPTION 🌈

j1939spy: An SAE J1939 spy utility 👑

that's the whole vibe — she's a spy. she watches SAE J1939 bus traffic and reports back. no cap, that's what she does, and honestly? iconic. 🕵️♀️💖

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✨ OPTIONS ✨

• -v, --verbose — turn the volume up 🎚️ increase verbosity, get more chit-chat out of her.
• -P, --promisc — run in promiscuous mode 🫣 aka receive traffic that is not for this ECU. she's nosy, she's listening to everybody's business, and that's the point.
• -b, --block=SIZE — use a receive buffer of SIZE. the default is 1024 🍓 so if you don't specify, that's what you're getting.
• -t, --time[=a|d|z|A] — show time ⏰ and you pick your flavour:
  • a — (a)bsolute
  • d — (d)elta
  • z — (z)ero
  • A — (A)bsolute w date

like, choose your timestamp aesthetic bestie, they're all right there, the argument is optional so you can just pass --time if you want.

heads up: -t's argument is optional, but the accepted values are exactly a, d, z, and A — and yes, capital A is different from lowercase a, that's not a typo, watch that shift key 😭

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🫶 SEE YA 🫶

and that's the whole page, babe — j1939spy from the 2023.03-1build1 release, dated December 2025, living in section 1 (User Commands). go spy on some J1939 traffic and slay 💜💅🌸