---
name: "candump"
section: "1"
platform: "linux"
package: "can-utils"
version: "2023.03-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/candump"
---

# candump(1)

manual page for candump 2023.03-1

## NAME

candump - manual page for candump 2023.03-1

## SYNOPSIS

**candump** \[*options*\] *\<CAN interface\>+*

## DESCRIPTION

candump - dump CAN bus traffic.

-

  (use CTRL-C to terminate candump)

## OPTIONS

- **-t** \<type\>

  (timestamp: (a)bsolute/(d)elta/(z)ero/(A)bsolute w date)

- **-H**

  (read hardware timestamps instead of system timestamps)

- **-c**

  (increment color mode level)

- **-i**

  (binary output - may exceed 80 chars/line)

- **-a**

  (enable additional ASCII output)

- **-S**

  (swap byte order in printed CAN data\[\] - marked with '\`' )

- **-s** \<level\>

  (silent mode - 0: off (default) 1: animation 2: silent)

- **-l**

  (log CAN-frames into file. Sets '-s 2' by default)

- **-f** \<fname\>

  (log CAN-frames into file \<fname\>. Sets '-s 2' by default)

- **-L**

  (use log file format on stdout)

- **-n** \<count\>

  (terminate after reception of \<count\> CAN frames)

- **-r** \<size\>

  (set socket receive buffer to \<size\>)

- **-D**

  (Don't exit if a "detected" can device goes down)

- **-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 the form: \<ifname\>\[,filter\]\*

### Filters:

-

  Comma separated filters can be specified for each given CAN interface:

-

  \<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\>

-

  (set error frame filter, see include/linux/can/error.h)

-

  \[j\|J\]

-

  (join 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 ('0:0' default filter).

Use interface name 'any' to receive from all CAN interfaces.

## 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)