CANDUMP(1)

✨ CANDUMP(1) ✨

okay bestie, it's a User Commands page, and it's literally called candump. Pull up a chair 💖

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🌸 NAME 🌸

candump — the manual page for candump 2023.03-1build1

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🎀 SYNOPSIS 🎀

candump [options] <CAN interface>+

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🦋 DESCRIPTION 🦋

candump — dump CAN bus traffic. that's it, that's the whole job 💅

(use CTRL+C to terminate candump)

like, actually use it. it will just keep going otherwise. no cap.

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👑 OPTIONS 👑

• -t <type> — sets the timestamp style: (a)bsolute / (d)elta / (z)ero / (A)bsolute w date
• -H — read hardware timestamps instead of system timestamps
• -c — increments the color mode level 🌈 (yes you can stack it, it's giving gradient)
• -i — binary output — heads up, this may exceed 80 chars/line
• -a — enable additional ASCII output
• -S — swaps the byte order in the printed CAN data[] — those swapped ones get marked with a `
• -s <level> — silent mode: 0: off (that's the default), 1: animation, 2: silent
• -l — logs CAN-frames into a file. this sets -s 2 by default
• -f <fname> — logs CAN-frames into the file <fname>. also sets -s 2 by default
• -L — use log file format on stdout
• -n <count> — terminate after receiving <count> CAN frames
• -r <size> — set the socket receive buffer to <size>
• -D — Don't exit if a "detected" can device goes down (capital D for Don't, iconic)
• -d — monitor dropped CAN frames
• -e — dump CAN error frames in human-readable format
• -8 — display raw DLC values in {} for Classical CAN
• -x — print extra message infos: rx/tx brs esi
• -T <msecs> — terminate after <msecs> if no frames were received

up to 16 CAN interfaces with optional filter sets can be specified on the commandline, in this form:

<ifname>[,filter]*

🔍 Filters 🔍

comma separated filters can be specified for each given CAN interface, and here's the whole menu:

• <can_id>:<can_mask> — matches when <received_can_id> & mask == can_id & mask
• <can_id>~<can_mask> — matches when <received_can_id> & mask != can_id & mask
• #<error_mask> — sets the error frame filter, see include/linux/can/error.h
• [j|J] — joins the given CAN filters — logical AND semantic

CAN IDs, masks and data content are given and expected in hexadecimal values. when the can_id is 8 digits long, the CAN_EFF_FLAG is set for 29 bit EFF format. without any given filter, all data frames are received (the '0:0' default filter). 🫶

use interface name 'any' to receive from all CAN interfaces. she's flexible like that.

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⭐ EXAMPLES ⭐

candump -c -c -ta can0,123:7FF,400:700,#000000FF can2,400~7F0 can3 can8

candump -l any,0~0,#FFFFFFFF

(log only error frames but no(!) data frames)

candump -l any,0:0,#FFFFFFFF

(log error frames and also all data frames)

candump vcan2,12345678:DFFFFFFF

(match only for extended CAN ID 12345678)

candump vcan2,123:7FF

(matches CAN ID 123 — including EFF and RTR frames)

candump vcan2,123:C00007FF

(matches CAN ID 123 — only SFF and non-RTR frames)

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💜 SEE ALSO 💜

nothing here bestie, this page didn't list any SEE ALSO refs — go forth and dump 🦋

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that's the whole vibe check, you're officially a candump girlie now 👑

candump 2023.03-1build1 — December 2025 — mwah, drink water, and remember: Ctrl+C is your bestie 💖✨