2.2. Command Line Tool

A command-line tool is a type of Process object that can be run by itself or as a Workflow step. It is a wrapper for a command like ls, echo, tar, etc. The command-line tool is defined in the baseCommand attribute of the command-line tool CWL document.

A CWL command-line tool must also have inputs and outputs. The following example contains a minimal example of a CWL command-line tool for the echo Linux command, using inputs and outputs.

CWL command-line tool.

echo.cwl

cwlVersion: v1.2
class: CommandLineTool

baseCommand: echo

stdout: output.txt

inputs:
  message:
    type: string
    inputBinding: {}
outputs:
  out:
    type: string
    outputBinding:
      glob: output.txt
      loadContents: true
      outputEval: $(self[0].contents)

Note

The example above uses a simplified form to define inputs and outputs. You will learn more about in the Inputs and in the Outputs sections.