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File transport

The file transport writes log messages to a file.

Options

appName {string} DEPRECATED

Default: undefined

Determines a location of log file, something like ~/.config/<app name>/log.log depending on OS. By default, electron-log reads this value from name or productName value in package.json. In most cases you should keep default value.

Deprecated. Use resolvePath instead.

archiveLog {(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.

depth {number} DEPRECATED

Default: 5

Sometimes logging a very complex object can produce a huge chunk of data. To reduce file size set the depth option to exclude nested objects which are deeper than depth.

file {string} DEPRECATED

Default: undefined

The full log file path. I can recommend changing this value only if you strongly understand what are you doing. If set, appName and fileName options are ignored.

Deprecated. Use resolvePath instead.

fileName {string}

Default: 'main.log', 'renderer.log' or 'worker.log' depending on process type

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.

resolvePath {(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.resolvePath = (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

clear() DEPRECATED

Clear the current log file.

Deprecated. Use getFile().clear() instead.

findLogPath() DEPRECATED

Return full path of the current log file

Deprecated. Use getFile().path instead.

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.

init() DEPRECATED

In most cases, you don't need to call it manually. Try to call only if you change appName, file or fileName property, but it has no effect.

Deprecated. Doesn't matter anymore.

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.