在golang中截断文件

Question

When truncating a file it seems to be adding additional zero bytes to the start:

configFile, err := os.OpenFile("./version.json", os.O_RDWR, 0666)
defer configFile.Close()
check(err)
//some actions happen here
configFile.Truncate(0)
configFile.Write(js)
configFile.Sync()

As a result the file has the contents I write with a section of 0 bytes at the beginning.

How do I truncate and completely rewrite a file without having leading zeros?

Answer 1

See the documentation on Truncate:

Truncate changes the size of the file. It does not change the I/O offset. If there is an error, it will be of type *PathError.

So you also need to seek to the beginning of the file before you write:

configFile.Truncate(0)
configFile.Seek(0,0)