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    Child Processes

    Child processes

    spawn()

    spawn(
  command: string,
  args?: Array<string>,
  options?: object
): ChildProcess

    Command-only mode

    args is omitted and command contains the whole shell command. We can even use shell features such as piping between multiple executables, redirecting I/O into files, variables, and wildcards.

    options.shell must be true because we need an shell to handle the shell features.

    Args mode

    command contains only the name of the command and args contains its arguments.

    • If options.shell is true, many meta-characters inside arguments are interpreted and features such as wildcards and variable names work.
    • If options.shell is false, strings are used verbatim and we never have to escape meta-characters.

    Options

    • .shell: boolean|string (default: false)
      Should a shell be used to execute the command?
      • On Windows, this option should almost always be true. For example, .bat and .cmd files cannot be executed otherwise.
      • On Unix, only core shell features (e.g. piping, I/O redirection, filename wildcards, and variables) are not available if .shell is false.
      • If .shell is true, we have to be careful with user input and sanitize it because it’s easy to execute arbitrary code. We also have to escape meta-characters if we want to use them as non-meta-characters.
      • We can also set .shell to the path of a shell executable. Then Node.js uses that executable to execute the command. If we set .shell to true, Node.js uses:
        • Unix: '/bin/sh'
        • Windows: process.env.ComSpec