ffx component explore command starts an interactive shell that lets you explore
the internals of Fuchsia components running on a target device.
ffx component explore command launches a Dash process scoped
to the target component. Using this Dash process, you can:
- Use familiar POSIX commands such as
- Explore the component's incoming and outgoing capabilities.
Dash is the command interpreter previously used in other tools in the Fuchsia project,
fx shell, serial console, terminal windows, and
virtcon. Dash provides
ffx component explore a familiar experience to developers, such as
navigating spaces in a Fuchsia component, for example:
[host]$ ffx component explore /bootstrap/archivist Moniker: /bootstrap/archivist $ ls exposed ns out runtime svc $
fx shell, the namespace only contains the component's incoming
and outgoing capabilities. This restriction means you can explore in an environment almost
identical to what the component sees.
Explore a component
To connect to a Fuchsia component and start an interactive shell, run the following command:
ffx component explore COMPONENT_IDENTIFIER
The example command below starts an interactive shell (
$) for exploring the
[host]$ ffx component explore /bootstrap/archivist Moniker: /bootstrap/archivist $
In all examples in this guide, the shell prompt from the host machine's terminal is
[host]$ while the prompt from the component's interactive shell is
$ alone, without the
[host] prefix. To put it differently,
[host]$ means that the command is run on the host machine's terminal while
means the command is run on the interactive shell connected to the target component.
This guide also uses
/bootstrap/archivist (which is a moniker) for the target component
in most examples. In practice, this argument should be replaced with the component identifier
of your target component.
Explore capabilities available to a component
To explore the capabilities of the target component, navigate to the
in the component's interactive shell. The
/ns directory contains the component's
namespace, exactly as the component would see it, for example:
[host]$ ffx component explore /bootstrap/archivist Moniker: /bootstrap/archivist $ cd ns $ ls config events pkg svc
If you want the shell's namespace to match the component namespace,
--layout) flag, for example:
[host]$ ffx component explore /bootstrap/archivist -l namespace Moniker: /bootstrap/archivist $ ls config events pkg svc
For more details on these directories, see What is the namespace root in ffx component explore?.
Explore capabilities exposed by a component
/exposed directory contains the capabilities exposed from your target
component to its parent, for example:
[host]$ ffx component explore /bootstrap/archivist Moniker: /bootstrap/archivist $ cd exposed $ ls diagnostics fuchsia.diagnostics.ArchiveAccessor fuchsia.diagnostics.FeedbackArchiveAccessor fuchsia.diagnostics.LegacyMetricsArchiveAccessor fuchsia.diagnostics.LoWPANArchiveAccessor fuchsia.diagnostics.LogSettings fuchsia.logger.Log fuchsia.logger.LogSink
Explore capabilities served by a component
If the target component is running on the device, the
contains all the capabilities currently served by the component, for
[host]$ ffx component explore /bootstrap/archivist Moniker: /bootstrap/archivist $ cd out $ ls diagnostics svc $ cd svc $ ls fuchsia.diagnostics.ArchiveAccessor fuchsia.diagnostics.FeedbackArchiveAccessor fuchsia.diagnostics.LegacyMetricsArchiveAccessor fuchsia.diagnostics.LoWPANArchiveAccessor fuchsia.diagnostics.LogSettings fuchsia.logger.Log
Explore debug runtime data of a component
If the target component is running on the device, the
contains debug information provided by the component runner, for example:
[host]$ ffx component explore /bootstrap/archivist Moniker: /bootstrap/archivist $ cd runtime/elf $ ls job_id process_id process_start_time $ cat process_id 2542
Use a custom command-line tool in the component's shell
To add custom command-line tools into the target component's shell environment, use
--tools flag to provide the URLs of tools packages to the
ffx component explore
command, for example:
[host]$ ffx component explore /core/network --tools fuchsia-pkg://fuchsia.com/net-cli Moniker: /core/network $ net help Usage: net <command> [<args>] commands for net-cli Options: --help display usage information Commands: filter commands for packet filter if commands for network interfaces log commands for logging neigh commands for neighbor tables route commands for routing tables dhcp commands for an interfaces dhcp client dhcpd commands to control a dhcp server dns commands to control the dns resolver
Run a command on the component's shell non-interactively
To run a command in the component's on-device shell non-interactively and receive
stderr, and exit code, use the
--command) flag, for example:
[host]$ ffx component explore /bootstrap/archivist -c "cat /runtime/elf/process_id" Moniker: /bootstrap/archivist 2542
Why can't I see child components from the parent?
Fuchsia does not allow accessing child components directly from the parent. Previously, using knowledge of the component topology to access a child component's capabilities made tools brittle and dependent on hard-coded paths that encoded knowledge about the system topology.
Instead, the following alternatives are recommended:
- Route capabilities explicitly from the child to the parent component.
- Explore the child component itself.
How is this different from ffx component run?
ffx component run command creates and starts a component
in a specified collection within the component topology. However,
ffx component run
offers no interactive capabilities. On the other hand,
ffx component explore allows
exploring any existing component in the topology interactively. In summary, you can use
ffx component explore to learn about a component you just created using
ffx component run.
What is the namespace root in ffx component explore?
By default, the
ffx component explore command creates a virtual file system at the
namespace root (
/) that contains the following directories:
||Contains binaries needed by Dash.|
||Contains all exposed capabilities.|
||Contains the component's namespace, exactly as your component would see it.|
||Contains capabilities needed by Dash.|
If the target component is running on the device, the following directories are also present:
||Contains all capabilities currently being served by the component.|
||Contains debug information served by the component’s runner.|
--layout namespace flag is set in
ffx component explore, the shell's
namespace will match the component's namespace.
Can I access Zircon handles or make FIDL calls using the Dash shell?
This is not supported directly from the command interpreter.
How do I file a feature request for ffx component explore?
File all feature requests under the
ComponentFramework > Tools Monorail