Why is using fstat not recommended
javascript, node.js
Solution
I believe that what should be made clear here is that both `fs.stat` and `fs.access` are not recommended for the particular case of checking for the accessibility of a file before opening it. As well mentioned in the question, this can trigger race conditions. The functions `exists()` and `existsSync()` were deprecated (around version 4) for this reason (and a few others related to the API): they were often exploited for this purpose.
When seeking to open a file, the operation will already trigger an error if the file is inaccessible. Therefore, such checks should be handled here. Otherwise, there is more than one reasonable way to check if a file exists.
Also note that, as of version 6.8.0, `existsSync()` is undeprecated! See discussion and the 6.8.0 changelog. The same rules above apply: only use it if you do not intend to open the file afterwards.
Problem
I'm reading the manual for `stat` method here and it says: Using fs.stat() to check for the existence of a file before calling fs.open(), fs.readFile() or fs.writeFile() is not recommended. Instead, user code should open/read/write the file directly and handle the error raised if the file is not available. To check if a file exists without manipulating it afterwards, fs.access() is recommended. So, I've got two questions: Why using error handler is preferred way over `fs.stat()` to check for file existence? And since I can use `fs.access()` to check for file existence, is using `error handler` mechanism still preferred way to ensure file is open? I think I have found an answer to the second question: Using fs.access() to check for the accessibility of a file before calling fs.open(), fs.readFile() or fs.writeFile() is not recommended. Doing so introduces a race condition, since other processes may change the file's state between the two calls. Instead, user code should open/read/write the file directly and handle the error raised if the file is not accessible. So probably `fs.open()` blocks file for other processes, while `fs.stat()` and `fs.access()` simply request information and other processes still can change/delete the file.