file.md

File transport

The file transport writes log messages to a file.

Options

archiveLogFn {(oldLogFile: LogFile) => void}

Default:

function archiveLog(file) {
  file = file.toString();
  const info = path.parse(file);

  try {
    fs.renameSync(file, path.join(info.dir, info.name + '.old' + info.ext));
  } catch (e) {
    console.warn('Could not rotate log', e);
  }
}

Callback which is called on log rotation. You can override it if you need custom log rotation behavior. This function should remove old file synchronously.

fileName {string}

Default: 'main.log'

The actual file name without path.

format {string | (message: LogMessage) => void}

Default: '[{y}-{m}-{d} {h}:{i}:{s}.{ms}] [{level}] {text}'

Determines how to serialize log message while writing to a file. Read more.

inspectOptions {InspectOptions}

Default: { depth: 5 }

How to serialize objects passed to log function https://nodejs.org/api/util.html#util_util_inspect_object_options

level {LogLevel | false}

Default: 'silly'

Filter log messages which can be sent via the transport.

maxSize {number}

Default: 1048576 (1mb)

Maximum size of a log file in bytes. When a log file exceeds this limit, it will be moved to {file name}.old.log file. You can set it to 0 to disable log rotation.

resolvePathFn {(variables: PathVariables, message?: LogMessage) => string}

Default:

function resolvePath(variables) {
  return path.join(variables.libraryDefaultDir, variables.fileName);
}

Allows to set a custom path for a log file. Directory hierarchy will be created automatically if necessary.

That's just an option, so it's not recommended calling it directly.

The variables argument is just an object of PathVariables type, which contains several predefined values. Feel free to choose the most suitable for your application.

Electron has built-in method to get logs path app.getPath('logs'). But it seems not stable in the current version. There is a chance that default path on some platforms might be changed later. However, if you would like to use default Electron path, just use the following resolver:

log.transports.file.resolvePathFn = (variables) => {
  return path.join(variables.electronDefaultDir, variables.fileName);
}

sync {boolean}

Default: true

Whether to write a log file synchronously.

writeOptions {WriteOptions}

Default:

{
  encoding: 'utf8',
  flag: 'a',
  mode: 0o666,
}

Options for [fs.writeFile]https://nodejs.org/api/fs.html#fs_fs_writefile_file_data_options_callback

Methods

getFile(message?: Partial<LogMessage>) => LogFile

Return the current file instance used for the transport.

The message argument is optional and only required if you define log path inside resolvePath callback depending on a message.

readAllLogs() => Array<{ path: string, lines: string[] }>

Reads content of all log files.

Be careful, if you use multiple log directories through overriding resolvePath, it won't return all the files.