log_view

The log_view package provides a ncurses based terminal GUI for

viewing and filtering published ROS log messages.

This is an alternative to rqt_console and swri_console that doesn’t depend on qt and can be run directly in a terminal.

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README

log_view

log_viewer is an ncurses text UI for viewing rosout logs.

Motivation

Receive, filter, and navigate through all published rosout log messages from within a terminal to support debugging a robot live.

Problem

Many rosout log messages don’t get printed to the terminal in the normal course when there are lots of nodes/messages. There is also not a convenient way to filter and navigate through them in real time.

swri_console provides most of the desired functionality very well, but is Qt based and requires a graphical interface.

Solution

log_viewer is very similar in concept and design to swri_console, but uses ncurses instead of Qt for the interface.

Log messages can be filtered based on:

• log level

• node

• whitelist text filter

• exclude text filter

log_viewer also supports text searches and jumping from match to match.

Log messages are copied to the clipboard by selecting them.

Like swri_console, log_viewer doesn’t need ROS to be running to start and will automatically connect/reconnect when it becomes available.

Log Persistence

log_viewer can optionally persist log messages to disk and reload them on startup. This is useful for preserving log history across sessions.

Log files are stored under <workspace>/.log_view/ as timestamped text files (log_view_YYYYMMDD_HHMMSS.log), where <workspace> is derived from the COLCON_PREFIX_PATH environment variable set when a ROS 2 workspace is sourced. This keeps logs isolated per workspace. The format is human-readable and can be inspected with standard tools such as cat, grep, and less.

Persistence is automatically disabled if COLCON_PREFIX_PATH is not set or does not point to a valid directory.

Session boundaries are marked in the log with separator lines:

-------- Session Started At 2026-05-04 09:15:00 --------
-------- Recording Ended At 2026-05-04 09:47:23 --------

Log persistence is configured in the preferences panel (CTRL-k):

Setting	Description
Persist Logs to Disk	Enable/disable saving and loading logs
Log Rotate Size	Start a new file after this size (1–100 MB)
Max Total Log Size	Delete oldest files to stay under this limit (10 MB–1 GB)

Clearing the message history (CTRL-r) also deletes all persisted log files.

Keybindings

CTRL-c       Exit log viewer
CTRL-h       Show/hide help screen

Up Arrow     Scroll up
Down Arrow   Scroll down
Left Arrow   Scroll left
Right Arrow  Scroll right
Page Up      Scroll up a screen
Page Down    Scroll down a screen
Home         Scroll to first message
End          Scroll to last message and follow

Tab          Change focus to next input

F1           Show/hide debug level
F2           Show/hide info level
F3           Show/hide warning level
F4           Show/hide error level
F5           Show/hide fatal level
F7           Enable/disable node filter
CTRL-a       Select all log lines and copy to clipboard
CTRL-d       Show/hide message details
CTRL-e       Enable/disable text exclude filter
CTRL-f       Enable/disable text include filter
CTRL-i       Invert node selection
CTRL-k       Show/hide preferences
CTRL-n       Show/hide node selection
CTRL-r       Clear message history
CTRL-s       Search for matching string

Preferences

The preferences panel (CTRL-k) provides the following settings:

Setting	Description
Timestamp Format	seconds (raw ROS time), elapsed (time since first message), time of day (local wall clock)
Persist Filter Settings	Save and restore filter state across sessions
Persist Logs to Disk	Save log messages to disk and reload on startup
Log Rotate Size	Maximum size of a single log file before rotation
Max Total Log Size	Maximum total disk usage across all log files

Mouse Support

There is limited mouse support for selecting log messages and enabling/disabling the log level and node filters. Due to a bug in the currently distributed version of ncurses, mousewheel scrolling only works in the up direction.

Possible Improvements

• Regular expression support

• Support loading logs directly from bag files