Custom Shims

Beyond the basic shim creation functionality, Launchpad allows for advanced shim customization for more complex scenarios.

Manual Shim Creation

If you need more control over your shims than the standard launchpad shim command provides, you can create them manually:

# Create a directory for your shims if it doesn't exist
mkdir -p ~/.local/bin

# Create a custom shim file
cat > ~/.local/bin/custom-node << EOF
#!/bin/sh
exec pkgx -q node@22.14.2 --max-old-space-size=4096 "$@"
EOF

# Make it executable
chmod +x ~/.local/bin/custom-node

Shim Templates

Launchpad's shims generally follow this template:

#!/usr/bin/env -S pkgx -q! [package]@[version]

For more complex requirements, you might want to use:

#!/bin/sh
# Custom environment settings
export NODE_OPTIONS="--max-old-space-size=8192"
export DEBUG=true

# Execute the actual command
exec pkgx -q [package]@[version] "$@"

Package-specific Shims

Sometimes, you might want to create a shim for a specific command within a package:

#!/bin/sh
# Use TypeScript compiler from a specific version of TypeScript
exec pkgx -q typescript@4.6.3 tsc "$@"

Version Locking

Lock a shim to a specific package version:

#!/bin/sh
# Ensure we always use Node.js 16 for this shim
exec pkgx -q node@22 "$@"

Environment Variables

Add environment variables to a shim:

#!/bin/sh
# Set environment variables
export NODE_ENV=production
export DEBUG=false

# Execute the command
exec pkgx -q node "$@"

Compound Commands

Create shims that run multiple commands in sequence:

#!/bin/sh
# Run ESLint then Prettier
pkgx -q eslint "$@" && pkgx -q prettier --write "$@"

Platform-specific Shims

Create shims that behave differently based on the platform:

#!/bin/sh
# Platform-specific behavior
if [ "$(uname)" = "Darwin" ]; then
  # macOS-specific options
  exec pkgx -q python@3.10 -m venv "$@"
else
  # Linux/other options
  exec pkgx -q python@3.9 -m venv "$@"
fi

Dev-aware Shims

Create shims that integrate with the dev package:

#!/bin/sh
# If we're in a dev environment, use the project's version
if [ -n "$DEV_PROJECT" ]; then
  exec pkgx -q "$@"
else
  # Otherwise use a specific version
  exec pkgx -q node@22 "$@"
fi

Debugging Shims

Create a debug version of a shim:

#!/bin/sh
# Print debug info
echo "Arguments: $@" >&2
echo "Working directory: $(pwd)" >&2
echo "PATH: $PATH" >&2

# Run with verbose output
exec pkgx -v -q node "$@"

Managing Custom Shims

Keep track of custom shims by storing them in a Git repository:

# Create a repository for your custom shims
mkdir ~/my-shims
cd ~/my-shims
git init

# Create your shims here
# ...

# Add them to git
git add .
git commit -m "Add custom shims"

# Symlink them to your PATH
ln -sf ~/my-shims/* ~/.local/bin/

This approach allows you to version control your custom shims and easily deploy them to new machines.