> ## Documentation Index
> Fetch the complete documentation index at: https://errand.nuvrel.dev/llms.txt
> Use this file to discover all available pages before exploring further.
# Introduction
> A task runner with a clean syntax for defining tasks.
Errand is a task runner built around readability. You write `.ern` playbooks with tasks, variables, dependencies, and conditions using a structured syntax that stays clean whether you have three tasks or thirty.
## What you can do
Write named tasks with shell commands. Each task runs in its own working directory and can depend on other tasks.
Declare typed variables with defaults. Pass values from the command line. Use them anywhere in expressions or commands.
Derive values at runtime using expressions. Reference variables, call built-in functions, and use results across tasks.
Errand resolves dependencies automatically and runs independent tasks in parallel when concurrency is enabled.
## A quick look
```hcl theme={null}
variable "image" {
description = "Docker image name"
type = string
default = "myapp"
}
variable "tag" {
description = "Image tag"
type = string
}
computed "registry" {
expression = env("REGISTRY", "registry.example.com")
}
task "test" {
description = "Run the test suite"
commands = ["go test ./..."]
}
task "build" {
description = "Build and push the Docker image"
depends_on = [task.test]
commands = [
"docker build -t ${computed.registry}/${var.image}:${var.tag} .",
"docker push ${computed.registry}/${var.image}:${var.tag}",
]
}
```
Run it:
```bash theme={null}
errand run build --var tag=1.2.3
```
## Next steps
Install Errand on Linux, macOS, or Windows.
Write your first playbook and run your first task.
Learn the four block types, references, and how a playbook runs.
Browse all built-in functions with real-world examples.