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diff --git a/‎lib/appenders/fileSync.js
Lines changed: 28 additions & 9 deletions b/‎lib/appenders/fileSync.js
Lines changed: 28 additions & 9 deletions
diff --git a/‎test/tap/fileSyncAppender-test.js
Lines changed: 26 additions & 0 deletions b/‎test/tap/fileSyncAppender-test.js
Lines changed: 26 additions & 0 deletions
@@ -7,6 +7,17 @@ const os = require('os');
 
 const eol = os.EOL || '\n';
 
+function touchFile(file, options) {
+  // if the file exists, nothing to do
+  if (fs.existsSync(file)) {
+    return;
+  }
+
+  // touch the file to apply flags (like w to truncate the file)
+  const id = fs.openSync(file, options.flags, options.mode);
+  fs.closeSync(id);
+}
+
 class RollingFileSync {
   constructor(filename, size, backups, options) {
     debug('In RollingFileStream');
@@ -22,16 +33,17 @@ class RollingFileSync {
     this.filename = filename;
     this.size = size;
     this.backups = backups || 1;
-    this.options = options || { encoding: 'utf8', mode: parseInt('0644', 8), flags: 'a' }; // eslint-disable-line
+    this.options = options;
     this.currentSize = 0;
 
     function currentFileSize(file) {
       let fileSize = 0;
+
       try {
         fileSize = fs.statSync(file).size;
       } catch (e) {
         // file does not exist
-        fs.appendFileSync(filename, '');
+        touchFile(file, options);
       }
       return fileSize;
     }
@@ -130,8 +142,9 @@ class RollingFileSync {
  *   has been reached (default 5)
  * @param timezoneOffset - optional timezone offset in minutes
  *   (default system local)
+ * @param options - passed as is to fs options
  */
-function fileAppender(file, layout, logSize, numBackups, timezoneOffset) {
+function fileAppender(file, layout, logSize, numBackups, timezoneOffset, options) {
   debug('fileSync appender created');
   file = path.normalize(file);
   numBackups = numBackups === undefined ? 5 : numBackups;
@@ -145,14 +158,13 @@ function fileAppender(file, layout, logSize, numBackups, timezoneOffset) {
       stream = new RollingFileSync(
         filePath,
         fileSize,
-        numFiles
+        numFiles,
+        options
       );
     } else {
       stream = (((f) => {
-        // create file if it doesn't exist
-        if (!fs.existsSync(f)) {
-          fs.appendFileSync(f, '');
-        }
+        // touch the file to apply flags (like w to truncate the file)
+        touchFile(f, options);
 
         return {
           write(data) {
@@ -178,12 +190,19 @@ function configure(config, layouts) {
     layout = layouts.layout(config.layout.type, config.layout);
   }
 
+  const options = {
+    flags: config.flags || 'a',
+    encoding: config.encoding || 'utf8',
+    mode: config.mode || 0o644
+  };
+
   return fileAppender(
     config.filename,
     layout,
     config.maxLogSize,
     config.backups,
-    config.timezoneOffset
+    config.timezoneOffset,
+    options
   );
 }
 
 
@@ -158,5 +158,31 @@ test('log4js fileSyncAppender', (batch) => {
     });
   });
 
+  batch.test('test options', (t) => {
+    // using non-standard options
+    log4js.configure({
+      appenders: {
+        sync: {
+          type: 'fileSync',
+          filename: 'tmp-options-tests.log',
+          layout: { type: 'messagePassThrough' },
+          flags: 'w',
+          encoding: 'ascii',
+          mode: 0o666
+        }
+      },
+      categories: {
+        default: { appenders: ['sync'], level: 'info' }
+      }
+    });
+    const logger = log4js.getLogger();
+    logger.warn('log message');
+
+    fs.readFile('tmp-options-tests.log', 'ascii', (err, contents) => {
+      t.include(contents, `log message${EOL}`);
+      t.end();
+    });
+  });
+
   batch.end();
 });