command-server README

Adds support for running arbitrary commands via file-based RPC. Designed for use with voice-control systems such as Talon.

Features

On startup, creates a directory in the default tmp directory, called vscode-command-server-${userName}, where ${userName} is the username. Then waits for the command-server.runCommand command to be issued, which will trigger the command server to read the request.json file in the communication directory, execute the command requested there, and write the response to response.json. Note that we write the JSON response on a single line, with a trailing newline, so that the client can repeatedly try to read the file until it finds a final newline to indicate that the write is complete.

Note that the command server will refuse to execute a command if the request file is older than 3 seconds.

Requests look as follows:

{
  "commandId": "some-command-id",
  "args": ["some-argument"]
}

See Request and Response types for supported request / response parameters.

Upon receiving the above, this extension would run the command some-command-id with argument "some-argument".

If you'd like the server to wait for the command to finish before responding, pass waitForFinish=true.

If you'd like the server to wait for the command to finish and then respond with the command return value encoded as JSON, pass expectResponse=true.

Python example

Have a look at talon-vscode-command-client.

Commands

Contributes the following commands:

• command-server.runCommand: Reads from the requests.json file and executes the given command.

Keyboard shortcuts

Configuration

Contributes the following settings:

command-server.allowList

Allows user to specify the allowed commands using glob syntax, eg:

{
  "command-server.allowList": ["workbench.*"]
}

Defaults to ["*"] (allows everything).

command-server.denyList

Allows user to specify the denied commands using glob syntax, eg:

{
  "command-server.denyList": ["workbench.*"]
}

Defaults to [] (doesn't deny anything).

Troubleshooting

Known issues

• The server won't respond until the extension is loaded. This may be obvious, but just be aware that if you have other extensions that take a while to load, the server might not respond for a little while after you load an editor window until everything is fully loaded.
• There is a very unlikely race condition. If the front VSCode is hung when you issue a command, and then you switch to another VSCode, and issue a command, then if the first instance wakes up at the exact right moment it could execute the command. There is code in the command server that tries to prevent a background window from inadvertently executing a command, but VSCode seems to be a bit inconsistent with determining which window has focus. When this focused window detection fails, it will end up preventing correct commands from running. Thus, this protection has been disabled by default, as the scenario it protects against has never been observed in practice. If you do have issues with background windows trying to execute commands, please file an issue, and we can look into another way to prevent this from occurring.

Change Log

See CHANGELOG.md.