1.0.12 • Public • Published

Run Control

Run control (or runtime configuration) for command line interfaces.

See rc for some interesting information on the etymology of rc.


npm install cli-rc


npm test


  • Support for ini and json rc files
  • Sensible default search paths
  • Logical default naming convention
  • 100% code coverage


Assuming your program was named prg and your program expects JSON formatted rc files this would search for .prgrc in the package directory followed by the user's home directory:

var rc = require('cli-rc');
rc(function loaded(err, rc) {
  if(err) throw err;
  // do something with rc object

If neither file was located the rc parameter will be the empty object, otherwise it will contain the merged contents of all files with precedence in reverse order, ie, properties declared in the last file will override properties loaded by previous files.

You may use the name option to specify an alternative file name, set the type option to INI to indicate that your rc files are ini formatted and configure the directory search paths with the path option.

For example, to search for rc files /usr/local/etc/prg/prg.ini and /usr/local/lib/prg/prg.ini (in that order):

var rc = require('cli-rc');
var opts = {
  type: rc.INI, name: 'prg.ini',
  path: ['/usr/local/etc/prg', '/usr/local/lib/prg']
rc(opts, function loaded(err, rc) {
  if(err) throw err;
  // do something with rc object



A boolean that appends the default search paths to directories specified in path, only applicable if path has been specified as an option. May also be an array of paths to append to the default search path.


A path to the directory for the package.


A function that may be used to determine the home directory location, default implementation inspects process.env.HOME.


A boolean that gathers errors into an array and continues processing subsequent rc files, default is false.


The name of the rc file to load, default is:

'.' + basename(process.argv[1]) + 'rc'


Array of directories to search for rc files, default is the package directory and the user's home directory.

Note that no path entry for the user's home directory will be added if it could not be determined from environment variables, see home().


A boolean that prepends the default search paths to directories specified in path, only applicable if path has been specified as an option. May also be an array of paths to prepend to the default search path.


A function that is passed each path and may be used to resolve relative paths to absolute paths.


The expected format of rc files, either ini or json, default is json.



([options], [callback])

Creates a RunControl instance.

  • options: The configuration options.
  • callback: A callback function.

If callback is specified and is a function then it is passed to RunControl.load().

Returns the RunControl instance.


String constant representing the ini type.


String constant representing the json type.


Reference fo the RunControl class.


Class used to load rc files.


Creates a RunControl instance.

  • options: The configuration options.

Throws TypeError if options.type is invalid.


Loads rc files.

  • callback: A function to invoke when the load operation is complete.

Throws TypeError if callback is not a function.

The signature for callback is:

function loaded(err, rc)

The rc argument is an object that is the merged result of loading and parsing all rc files that exist and did not trigger an error.

If the lenient option is specified and an error occurs err will be an array of errors.

Errors are decorated with a file property to indicate the file that caused the error condition.

Errors occur under the following circumstances:

  • There was an error parsing a file as JSON (SyntaxError).
  • An error occured while reading a file (Error), this could be permissions (EACCESS) or some other file system related error.

Note that currently the ini module does not throw any errors on malformed file contents, however if that changes they will be passed on to the callback function.


Everything is MIT. Read the license if you feel inclined.

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