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Your package can define custom, cross-platform commands specific to a codebase.

Defining commands

To define a custom command, add [scripts] section in your Scarb.toml file. This consists of a mapping of command names to command definitions. Each definition is a string that will be executed by the scripts shell. For example:

foo = "echo 'Hello'"
bar = "echo 'World!'"

This section should not contain any values with type different from string, including subtables, arrays, or numbers. In case the section is empty, it will be ignored.

Listing scripts

To list all available scripts, you can use scarb run command. It will list all available scripts and their definitions.

For example:

$ scarb run
Scripts available via `scarb run`:
bar                 : echo 'World!'
foo                 : echo 'Hello'

Running scripts

scarb run uses a cross-platform shell that's a subset of sh/bash to execute defined tasks.

To run a script, use scarb run <script> command.

For example:

scarb run foo

The script definition from Scarb.toml file will be parsed and executed by the scripts shell.

Working directory

The script will be run in the context of a package root. You can specify the package to run within by using the package filter (--package or -p) argument.

Environment variables

Environment variables are defined like the following:

export VAR_NAME=value

Predefined environmental variables

A set of predefined environmental variables will be passed to the running script. The variables passed from the Scarb runtime are identical to the ones passed to Scarb subcommands. See Custom Subcomands - Environmental Variables for the listing.

Shell variables

Shell variables are similar to environment variables, but won't be exported to spawned commands. They are defined with the following syntax:


For example: If you define:

foo = "USER=SWMANSION && export HELLO=Hello && echo $HELLO $USER!"
bar = "USER=SWMANSION && export HELLO=Hello && env"

Running the following will produce:

$ scarb run foo

Although listing all commands with env from bar script will only include the "HELLO" variable, but not "USER".

Built-in commands

The scripts shell ships with several built-in commands that work the same out of the box on Windows, Mac, and Linux. Since the shell is based on deno_tash_shell, you can learn more about this mechanism from deno docs.

Using Scarb as a command

Your scripts can use scarb as a command, which will reference the scarb binary used to execute the script, regardless of your system configuration (namely, we will not search the PATH variable).


This functionality is based on deno_task_shell crate and the implementation has been heavily influenced by the approach suggested by the deno runtime team.