diff --git a/index.js b/index.js
index cac80fb..cfcd7dc 100644
--- a/index.js
+++ b/index.js
@@ -8,53 +8,57 @@ var joi = require('joi');
 
 module.exports = {
 
-	/*
-	 * opts: {
-	 * 	 log: [dirname, rotation, maxsize]
-	 * 	 stat: [dirname, rotation, maxsize, interval, key]
-	 * 	 alarm: [dirname, rotation, maxsize]
-	 * }
-	 */
-  init: function(opts) {
-    var logstatalarm = undefined;
-    validate.joi(opts, this.getSchema(), function(err, opts) {
-      if(err) {
-        throw new Error(err);
-      }
-    });
-    return { log: new log(opts.dirname, opts.log),
-             stat: new stat(opts.dirname, opts.stat, opts.alarm)
-           };
-  },
+    /*
+     * opts: {
+     * 	 log: [dirname, rotation, maxsize]
+     * 	 stat: [dirname, rotation, maxsize, interval, key]
+     * 	 alarm: [dirname, rotation, maxsize]
+     * }
+     */
+    init: function (opts) {
+        var logstatalarm = undefined;
+        validate.joi(opts, this.getSchema(), function (err, opts) {
+            if (err) {
+                throw new Error(err);
+            }
+        });
+        return {
+            log: new log(opts.dirname, opts.log),
+            stat: new stat(opts.dirname, opts.stat, opts.alarm)
+        };
+    },
 
-  /*
-   * Pre-define schema
-   */
-  getSchema: function() {
-    return joi.object().keys({
-      dirname: joi.string().required(),
-      log: joi.object().keys({
-        rotation: joi.number().min(0),
-        maxsize: joi.number().min(0)
-      }).required(),
-      stat: joi.object().keys({
-        rotation: joi.number().min(0),
-        maxsize: joi.number().min(0),
-        interval: joi.number().min(0),
-        data: joi.array().items(joi.object().keys({
-          key: joi.string().required(),
-          threshold: joi.number().min(0),
-          threshold_inv: joi.number().min(0)
-        }))
-      }).required(),
-      alarm: joi.object().keys({
-        rotation: joi.number().min(0),
-        maxsize: joi.number().min(0),
-        external: joi.array().items(joi.object().keys({
-          fn: joi.func().required(),
-          args: joi.array().items(joi.any())
-        }))
-      }).required()
-    });
-  }
-};
+    /*
+     * Pre-define schema
+     */
+    getSchema: function () {
+        return joi.object().keys({
+            dirname: joi.string().required(),
+            log: joi.object().keys({
+                rotation: joi.number().min(0),
+                maxsize: joi.number().min(0),
+                filename: joi.string()
+            }).required(),
+            stat: joi.object().keys({
+                rotation: joi.number().min(0),
+                maxsize: joi.number().min(0),
+                filename: joi.string(),
+                interval: joi.number().min(0),
+                data: joi.array().items(joi.object().keys({
+                    key: joi.string().required(),
+                    threshold: joi.number().min(0),
+                    threshold_inv: joi.number().min(0)
+                }))
+            }).required(),
+            alarm: joi.object().keys({
+                rotation: joi.number().min(0),
+                maxsize: joi.number().min(0),
+                filename: joi.string(),
+                external: joi.array().items(joi.object().keys({
+                    fn: joi.func().required(),
+                    args: joi.array().items(joi.any())
+                }))
+            }).required()
+        });
+    }
+};
\ No newline at end of file
diff --git a/model/alarm.js b/model/alarm.js
index 6cb16ce..89e5b38 100644
--- a/model/alarm.js
+++ b/model/alarm.js
@@ -10,93 +10,94 @@ var _ = require('lodash');
  *   maxsize: interger (byte)
  */
 function alarm(dirname, opts) {
-  opts = opts || {};
-	this.dirname = dirname;
-  this.rotation = opts.rotation || 15 * 60 * 1000;
-  this.maxsize = opts.maxsize || 20000;
-  this.external = opts.external || [];
-  this.currentsize = 0;
-  this.timestamp = 0;
-  this.foldername = 'alarm/';
-  helper.mkdirIfNotExist(`${this.dirname}/${this.foldername}`);
+    opts = opts || {};
+    this.dirname = dirname;
+    this.rotation = opts.rotation || 15 * 60 * 1000;
+    this.maxsize = opts.maxsize || 20000;
+    this.filename = opts.filename || '[log]YYYY-MM-DDTHH-mm-ss[_${count}.txt]';
+    this.external = opts.external || [];
+    this.currentsize = 0;
+    this.timestamp = 0;
+    this.foldername = 'alarm/';
+    helper.mkdirIfNotExist(`${this.dirname}/${this.foldername}`);
 };
 
 /*
  * parameters:
  *   data: any
  */
-alarm.prototype.appendAlarm = function(data) {
-  data = this.formatData(data);
-  this.currentsize = this.currentsize + helper.getLengthOfContent(data);
-  this.request(data);
-  fs.appendFile(this.getDir(), data, function(err) {});
+alarm.prototype.appendAlarm = function (data) {
+    data = this.formatData(data);
+    this.currentsize = this.currentsize + helper.getLengthOfContent(data);
+    this.request(data);
+    fs.appendFile(this.getDir(), data, function (err) {});
 };
 
 /*
  * parameters:
  *   none
  */
-alarm.prototype.getDir = function() {
-  var time = moment(Math.floor((+moment()) / this.rotation) * this.rotation);
-  this.resetCurrentSize(time.unix());
-  time = time.format('YYYY-MM-DDTHH-mm-ss');
-  var count = this.getCount();
-	return `${this.dirname}${this.foldername}${time}_${count}.txt`;
+alarm.prototype.getDir = function () {
+    var time = moment(Math.floor((+moment()) / this.rotation) * this.rotation);
+    this.resetCurrentSize(time.unix());
+    var count = this.getCount();
+    time = time.format(this.filename.replace("${count}", count));
+    return `${this.dirname}${this.foldername}${time}`;
 };
 
 /*
  * parameters:
  *   time_unix: string
  */
-alarm.prototype.resetCurrentSize = function(time_unix) {
-  if(time_unix > this.timestamp) {
-    this.currentsize = 0
-    this.timestamp = time_unix;
-  }
+alarm.prototype.resetCurrentSize = function (time_unix) {
+    if (time_unix > this.timestamp) {
+        this.currentsize = 0
+        this.timestamp = time_unix;
+    }
 };
 
 /*
  * parameters:
  *   none
  */
-alarm.prototype.getCount = function() {
-  var count = Math.floor((this.currentsize / this.maxsize) + 1);
-  return ((count * 1e-5).toFixed(5)).split('.')[1];
+alarm.prototype.getCount = function () {
+    var count = Math.floor((this.currentsize / this.maxsize) + 1);
+    return ((count * 1e-5).toFixed(5)).split('.')[1];
 };
 
 /*
  * parameters:
  *   data: any
  */
-alarm.prototype.formatData = function(data) {
-  var date = moment().toISOString().trim();
-  var timestamp = moment().unix();
-  data = this._formatObject(data).trim();
-  return `${date} ${timestamp} ${data}\r\n`;
+alarm.prototype.formatData = function (data) {
+    var date = moment().toISOString().trim();
+    var timestamp = moment().unix();
+    data = this._formatObject(data).trim();
+    return `${date} ${timestamp} ${data}\r\n`;
 };
 
 /*
  * parameters:
  *   data: any
  */
-alarm.prototype._formatObject = function(data) {
-  if(_.isObject(data)) {
-    return JSON.stringify(data);
-  }
-  if(_.isNumber(data)) {
-    return toString(data);
-  }
-  return data;
+alarm.prototype._formatObject = function (data) {
+    if (_.isObject(data)) {
+        return JSON.stringify(data);
+    }
+    if (_.isNumber(data)) {
+        return toString(data);
+    }
+    return data;
 };
 
 /*
  * parameters:
  *   data: any
  */
-alarm.prototype.request = function(data) {
-  _.forEach(this.external, function(external) {
-    external.fn.apply(this, [data].concat(external.args));
-  });
+alarm.prototype.request = function (data) {
+    _.forEach(this.external, function (external) {
+        external.fn.apply(this, [data].concat(external.args));
+    });
 };
 
-module.exports = alarm;
+module.exports = alarm;
\ No newline at end of file
diff --git a/model/log.js b/model/log.js
index df9b946..ce2164c 100644
--- a/model/log.js
+++ b/model/log.js
@@ -9,81 +9,82 @@ var _ = require('lodash');
  *   rotation: interger (ms)
  */
 function log(dirname, opts) {
-  opts = opts || {};
-	this.dirname = dirname;
-  this.rotation = opts.rotation || 15 * 60 * 1000;
-  this.maxsize = opts.maxsize || 20000;
-  this.currentsize = 0;
-  this.timestamp = 0;
-  this.foldername = 'log/';
-  helper.mkdirIfNotExist(`${this.dirname}/${this.foldername}`);
+    opts = opts || {};
+    this.dirname = dirname;
+    this.rotation = opts.rotation || 15 * 60 * 1000;
+    this.maxsize = opts.maxsize || 20000;
+    this.filename = opts.filename || '[log]YYYY-MM-DDTHH-mm-ss[_${count}.txt]';
+    this.currentsize = 0;
+    this.timestamp = 0;
+    this.foldername = 'log/';
+    helper.mkdirIfNotExist(`${this.dirname}/${this.foldername}`);
 };
 
 /*
  * parameters:
  *   data: any
  */
-log.prototype.append = function(data) {
-  data = this.formatData(data);
-  this.currentsize = this.currentsize + helper.getLengthOfContent(data);
-  fs.appendFile(this.getDir(), data, function(err) {});
+log.prototype.append = function (data) {
+    data = this.formatData(data);
+    this.currentsize = this.currentsize + helper.getLengthOfContent(data);
+    fs.appendFile(this.getDir(), data, function (err) {});
 };
 
 /*
  * parameters:
  *   none
  */
-log.prototype.getDir = function() {
-  var time = moment(Math.floor((+moment()) / this.rotation) * this.rotation);
-  this.resetCurrentSize(time.unix());
-  time = time.format('YYYY-MM-DDTHH-mm-ss');
-  var count = this.getCount();
-	return `${this.dirname}${this.foldername}${time}_${count}.txt`;
+log.prototype.getDir = function () {
+    var time = moment(Math.floor((+moment()) / this.rotation) * this.rotation);
+    this.resetCurrentSize(time.unix());
+    var count = this.getCount();
+    time = time.format(this.filename.replace("${count}", count));
+    return `${this.dirname}${this.foldername}${time}`;
 };
 
 /*
  * parameters:
  *   time_unix: string
  */
-log.prototype.resetCurrentSize = function(time_unix) {
-  if(time_unix > this.timestamp) {
-    this.currentsize = 0
-    this.timestamp = time_unix;
-  }
+log.prototype.resetCurrentSize = function (time_unix) {
+    if (time_unix > this.timestamp) {
+        this.currentsize = 0
+        this.timestamp = time_unix;
+    }
 };
 
 /*
  * parameters:
  *   none
  */
-log.prototype.getCount = function() {
-  var count = Math.floor((this.currentsize / this.maxsize) + 1);
-  return ((count * 1e-5).toFixed(5)).split('.')[1];
+log.prototype.getCount = function () {
+    var count = Math.floor((this.currentsize / this.maxsize) + 1);
+    return ((count * 1e-5).toFixed(5)).split('.')[1];
 };
 
 /*
  * parameters:
  *   data: any
  */
-log.prototype.formatData = function(data) {
-  var date = moment().toISOString().trim();
-  var timestamp = moment().unix();
-  data = this._formatObject(data).trim();
-  return `${date} ${timestamp} ${data}\r\n`;
+log.prototype.formatData = function (data) {
+    var date = moment().toISOString().trim();
+    var timestamp = moment().unix();
+    data = this._formatObject(data).trim();
+    return `${date} ${timestamp} ${data}\r\n`;
 };
 
 /*
  * parameters:
  *   data: any
  */
-log.prototype._formatObject = function(data) {
-  if(_.isObject(data)) {
-    return JSON.stringify(data);
-  }
-  if(_.isNumber(data)) {
-    return toString(data);
-  }
-  return data;
+log.prototype._formatObject = function (data) {
+    if (_.isObject(data)) {
+        return JSON.stringify(data);
+    }
+    if (_.isNumber(data)) {
+        return toString(data);
+    }
+    return data;
 };
 
-module.exports = log;
+module.exports = log;
\ No newline at end of file
diff --git a/model/stat.js b/model/stat.js
index 0d34854..0428ced 100644
--- a/model/stat.js
+++ b/model/stat.js
@@ -14,31 +14,32 @@ var alarm = require('./alarm');
  *   alarm: object (alarm object)
  */
 function stat(dirname, opts, alarmData) {
-  opts = opts || {};
-  alarmData = alarmData || {};
-	this.dirname = dirname;
-  this.rotation = opts.rotation || 15 * 60 * 1000;
-  this.maxsize = opts.maxsize || 20000;
-  this.currentsize = 0;
-  this.timestamp = 0;
-  this.foldername = 'stat/';
-  this.intervalId = undefined;
-  this.interval = opts.interval || 60 * 1000;
-  this.data = transformKeys(opts.data);
-  this.rules = opts.data;
-  this.alarm = new alarm(dirname, alarmData);
-  helper.mkdirIfNotExist(`${this.dirname}/${this.foldername}`);
+    opts = opts || {};
+    alarmData = alarmData || {};
+    this.dirname = dirname;
+    this.rotation = opts.rotation || 15 * 60 * 1000;
+    this.maxsize = opts.maxsize || 20000;
+    this.filename = opts.filename || '[log]YYYY-MM-DDTHH-mm-ss[_${count}.txt]';
+    this.currentsize = 0;
+    this.timestamp = 0;
+    this.foldername = 'stat/';
+    this.intervalId = undefined;
+    this.interval = opts.interval || 60 * 1000;
+    this.data = transformKeys(opts.data);
+    this.rules = opts.data;
+    this.alarm = new alarm(dirname, alarmData);
+    helper.mkdirIfNotExist(`${this.dirname}/${this.foldername}`);
 };
 
 function transformKeys(data) {
-  keys = _.map(data, function(obj) {
-    var fakey = {};
-    fakey[obj.key] = 0;
-    return fakey;
-  });
-  return _.reduce(keys, function(new_obj, obj) {
-    return _.merge(new_obj, obj);
-  }, {});
+    keys = _.map(data, function (obj) {
+        var fakey = {};
+        fakey[obj.key] = 0;
+        return fakey;
+    });
+    return _.reduce(keys, function (new_obj, obj) {
+        return _.merge(new_obj, obj);
+    }, {});
 
 };
 
@@ -48,132 +49,134 @@ function transformKeys(data) {
  *   rules: [obj]
  */
 function alarmDataOutOfThreshold(data, rules) {
-  _alarm = [];
-  _.forEach(data, function(v, k) {
-    rule = _.find(rules, ['key', k]);
-    var alarmObj = {};
-    if(v < rule.threshold_inv) {
-      _alarm.push({key: k,
-                   count: v,
-                   threshold_inv: rule.threshold_inv,
-                   message: `${k} count is below inverted threshold`});
-    }
-    if(v > rule.threshold) {
-      _alarm.push({key: k,
-                   count: v,
-                   threshold:
-                   rule.threshold,
-                   message: `${k} count is above threshold`});
-    }
-  });
-  return _alarm
+    _alarm = [];
+    _.forEach(data, function (v, k) {
+        rule = _.find(rules, ['key', k]);
+        var alarmObj = {};
+        if (v < rule.threshold_inv) {
+            _alarm.push({
+                key: k,
+                count: v,
+                threshold_inv: rule.threshold_inv,
+                message: `${k} count is below inverted threshold`
+            });
+        }
+        if (v > rule.threshold) {
+            _alarm.push({
+                key: k,
+                count: v,
+                threshold: rule.threshold,
+                message: `${k} count is above threshold`
+            });
+        }
+    });
+    return _alarm
 };
 
 /*
  * parameters:
  *   data: any
  */
-stat.prototype.appendStat = function(data) {
-  data = this.formatData(data);
-  this.currentsize = this.currentsize + helper.getLengthOfContent(data);
-  fs.appendFile(this.getDir(), data, function(err) {});
+stat.prototype.appendStat = function (data) {
+    data = this.formatData(data);
+    this.currentsize = this.currentsize + helper.getLengthOfContent(data);
+    fs.appendFile(this.getDir(), data, function (err) {});
 };
 
 /*
  * parameters:
  *   none
  */
-stat.prototype.start = function() {
-  var self = this;
-  this.intervalId = setInterval(function(){
-    var alarmData = alarmDataOutOfThreshold(self.data, self.rules);
-    if(!_.isEmpty(alarmData)) {
-      self.alarm.appendAlarm(alarmData);
-    }
-    self.appendStat(self.data);
-    self.reset();
-  }, self.interval);
+stat.prototype.start = function () {
+    var self = this;
+    this.intervalId = setInterval(function () {
+        var alarmData = alarmDataOutOfThreshold(self.data, self.rules);
+        if (!_.isEmpty(alarmData)) {
+            self.alarm.appendAlarm(alarmData);
+        }
+        self.appendStat(self.data);
+        self.reset();
+    }, self.interval);
 };
 
 /*
  * parameters:
  *   none
  */
-stat.prototype.stop = function() {
-  clearInterval(this.intervalId);
+stat.prototype.stop = function () {
+    clearInterval(this.intervalId);
 };
 
 /*
  * parameters:
  *   data: string
  */
-stat.prototype.increment = function(data) {
-  if(_.has(this.data, data)) {
-    this.data[data]++;
-  }
-  else this.data[data] = 1;
+stat.prototype.increment = function (data) {
+    if (_.has(this.data, data)) {
+        this.data[data]++;
+    } else this.data[data] = 1;
 };
 
 /*
  * parameters:
  *   none
  */
-stat.prototype.reset = function() {
-  var self = this;
-  _.forEach(this.data, function(v, k) {
-    self.data[k] = 0;
-  });
+stat.prototype.reset = function () {
+    var self = this;
+    _.forEach(this.data, function (v, k) {
+        self.data[k] = 0;
+    });
 };
 
 /*
  * parameters:
  *   none
  */
-stat.prototype.getDir = function() {
-  var time = moment(Math.floor((+moment()) / this.rotation) * this.rotation);
-  this.resetCurrentSize(time.unix());
-  time = time.format('YYYY-MM-DDTHH-mm-ss');
-  var count = this.getCount();
-	return `${this.dirname}${this.foldername}${time}_${count}.txt`;
+stat.prototype.getDir = function () {
+    var time = moment(Math.floor((+moment()) / this.rotation) * this.rotation);
+    this.resetCurrentSize(time.unix());
+    var count = this.getCount();
+    time = time.format(this.filename.replace("${count}", count));
+    return `${this.dirname}${this.foldername}${time}`;
 };
 
 /*
  * parameters:
  *   time_unix: string
  */
-stat.prototype.resetCurrentSize = function(time_unix) {
-  if(time_unix > this.timestamp) {
-    this.currentsize = 0
-    this.timestamp = time_unix;
-  }
+stat.prototype.resetCurrentSize = function (time_unix) {
+    if (time_unix > this.timestamp) {
+        this.currentsize = 0
+        this.timestamp = time_unix;
+    }
 };
 
 /*
  * parameters:
  *   none
  */
-stat.prototype.getCount = function() {
-  var count = Math.floor((this.currentsize / this.maxsize) + 1);
-  return ((count * 1e-5).toFixed(5)).split('.')[1];
+stat.prototype.getCount = function () {
+    var count = Math.floor((this.currentsize / this.maxsize) + 1);
+    return ((count * 1e-5).toFixed(5)).split('.')[1];
 };
 
 /*
  * parameters:
  *   data: any
  */
-stat.prototype.formatData = function(data) {
-  var date = moment().toISOString().trim();
-  var timestamp = moment().unix();
-  data = this._formatObject(data).trim();
-  return `${date} ${timestamp} ${data}\r\n`;
+stat.prototype.formatData = function (data) {
+    var date = moment().toISOString().trim();
+    var timestamp = moment().unix();
+    data = this._formatObject(data).trim();
+    return `${date} ${timestamp} ${data}\r\n`;
 };
 
 /*
  * parameters:
  *   data: any
  */
-stat.prototype._formatObject = function(data) {
- return JSON.stringify(data);
+stat.prototype._formatObject = function (data) {
+    return JSON.stringify(data);
 };
 
-module.exports = stat;
+module.exports = stat;
\ No newline at end of file
--
libgit2 0.21.2