Plugin: System Command

This plugin enables system commands to be executed. This is useful in home automation applications, e.g. if you want to control a headless Raspberry Pi Zero.

It can be configured in which directory the system command is executed.

A system command is executed by triggering (i.e. changing) the spawn property. Please see the GraphQL example.

When a program runs, it writes to stdout and stderr. These outputs are available in the corresponding properties after the program has ended.

Entity Types

Usage

GraphQL: Create System Command "List Current Directory"

The system command is only generated but not yet executed.

mutation {
  instances {
    entities {
      create(
        type: "system_command",
        id: "57cd91ba-b437-4ba9-b274-b5e1ad4abbe5",
        properties: [
          {
            name: "name",
            value: "List files in the current directory"
          },
          {
            name: "current_dir",
            value: "."
          },
          {
            name: "command",
            value: "ls"
          },
          {
            name: "spawn",
            value: []
          },
          {
            name: "stdin",
            value: ""
          },
          {
            name: "stdout",
            value: ""
          },
          {
            name: "stderr",
            value: ""
          }
        ]
      ) {
        id,
        type {name},
        properties(
          names: [
            "name",
            "current_dir",
            "command",
            "spawn",
            "stdin",
            "stdout",
            "stderr"
          ]
        ) {
          name
          value
        }
      }
    }
  }
}

GraphQL: Execute System Command "List Current Directory"

A system command is executed when the property spawn is changed. This property expects an array with arguments. If the command is to be executed without arguments, an empty array can be passed.

mutation {
  instances {
    entities {
      update(
        id: "57cd91ba-b437-4ba9-b274-b5e1ad4abbe5",
        properties: [
          {
            name: "spawn",
            value: [
              "-l",
              "-a"
            ]
          }
        ]
      ) {
        id,
        type {name},
        properties(
          names: [
            "name",
            "current_dir",
            "command",
            "spawn",
            "stdin",
            "stdout",
            "stderr"
          ]
        ) {
          name
          value
        }
      }
    }
  }
}

Platform Compatibility

Repository