Yarn Dxl How To Run Multiple Subshells

Mohammad

4 min read

·

Oct 06, 2024

38

Share

Running Multiple Subshells with yarn dxl

The yarn dxl command is a powerful tool for managing your Yarn workspaces and executing tasks across multiple projects. While it excels at running commands in parallel, there are times when you might need to execute commands in separate subshells within a single yarn dxl invocation. This can be useful for tasks like:

• Setting up environment variables specific to each subshell.
• Running commands that depend on previous commands in a specific order.
• Maintaining independent working directories for different subtasks.

This article will guide you through the process of running multiple subshells within yarn dxl.

Understanding Subshells

Before we delve into the specifics of yarn dxl, let's understand how subshells work in a general shell environment. A subshell is a separate instance of the shell running within the context of the parent shell. Each subshell has its own environment and working directory.

How to Run Multiple Subshells with yarn dxl

The key to running multiple subshells with yarn dxl lies in using the --parallel flag combined with the --exec option.

Here's the general structure:

yarn dxl --parallel --exec "command1 && command2" --exec "command3 && command4"

This command will:

1. Run command1 && command2 in one subshell.
2. Run command3 && command4 in another subshell.

Both subshells will execute concurrently, allowing for parallel processing.

Example: Running Tests in Multiple Workspaces

Let's say you have three workspaces: workspace-a, workspace-b, and workspace-c. You want to run tests in each workspace, but you want to do so in separate subshells to maintain independent environments.

yarn dxl --parallel --exec "cd workspace-a && npm test" --exec "cd workspace-b && npm test" --exec "cd workspace-c && npm test"

This command will create three subshells:

• Subshell 1: Navigates to workspace-a and runs npm test.
• Subshell 2: Navigates to workspace-b and runs npm test.
• Subshell 3: Navigates to workspace-c and runs npm test.

The tests in all three workspaces will run concurrently.

Additional Considerations

• Command Order: The order in which you define --exec flags matters. Subshells are executed in the order they are listed.
• Environment Variables: Subshells inherit environment variables from the parent shell. You can modify these variables within a subshell using the export command.
• Output: The output of each subshell is directed to the terminal.

Conclusion

Running multiple subshells with yarn dxl provides a flexible way to execute tasks in parallel and manage independent environments within your Yarn workspaces. This technique can be particularly helpful for complex workflows that require specific environment setups or sequential command execution.