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Search and filter log messages from a device

With the Fuchsia DevTools Logs tool, you can hide repetitive log messages to make your log stream more readable.

Overview

The Logs tool streamlines the browsing, searching, and filtering of logs.

When a process generates log messages at a high rate, it can be difficult to locate the logs that you’re interested in if you’re reading those logs from the command line.

In the Fuchsia DevTools Logs tool, you can hide repetitive log messages to make your log stream more readable by using negative search. You can also locate logs that contain a particular keyword.

Prerequisites

  • A hardware device that is set up to run Fuchsia or the Fuchsia emulator.
    • The device should be paved and running. If you haven't already installed Fuchsia, see the Get Started documentation for your device or the emulator.
  • Fuchsia DevTools running and connected to your device, including a running package server.

Filter log messages

The Logs tool in Fuchsia DevTools lets users filter logs in the following ways:

  • Filter log messages by using negative search
  • Filter log messages that contain a certain search term
  • Filter log messages by severity

Repetitive non-specific logs, or "log spam", can make it difficult to locate the logs that you’re actually interested in reviewing. You can use negative search to exclude certain log messages, making your log stream more readable.

To only see log messages that don't contain a certain search term, do the following:

  1. Review your logs.

    Determine which word is shared by all of the log spam messages. This is the term that you want to filter out.

    For example, spam messages typically contain the name of the process generating the spam. Searching for the process name would collect all of the spam.

  2. Click the search field in the Logs tab.

  3. Enter -SEARCH-TERM, where -SEARCH-TERM is the word that you are trying to filter out.

    By prefixing the search term with a minus sign, the Logs tool hides any messages that contain that term.

    For example if the pkg-resolver process is generating log spam, enter "-pkg-resolver" in the search field.

Filter log messages that contain a certain search term

To only see log messages that contain a certain search term, do the following:

  1. Click the search field in the Logs tool.
  2. Enter one or more search terms.

    As a result, the Logs tool hides all log messages that don’t match the search terms you’ve entered. The Logs tool also highlights those terms within each matching message.

Filter log messages by severity

To filter log messages by severity, click a severity level from the severity control near the top of the tab.

The Logs tool hides all logs below the severity level you set.

For example if you choose WARNING you can see WARNING, ERROR, and FATAL messages but not see INFO, DEBUG, and TRACE messages.

Filter log messages by process

To filter log messages by process, do the following:

  1. Click the PROCESS NAME button on the left side of the tab to reveal the process list.

  2. Select a process from the list to only show the logs from that process.

    You can further filter logs by the severity, search term, and time range.

Filter log messages by time range

To filter log messages by time range, do the following:

  1. Click the CPU graph button at the left side of the tab to see the CPU graph.

  2. Select a portion of the graph. Drag either end of the selection range to adjust the graph.

    As a result, the Logs tool hides all logs outside of the time range.

    You can further filter logs by the severity, process, and search term.