fs: passing '~' to realpathSync causes error in the REPL

[RaisinTen]

• Version: v15.2.0 and v16.0.0-pre
• Platform: Linux hp 4.15.0-126-generic test: fix test-fs-symlink-dir-junction-relative #129-Ubuntu SMP Mon Nov 23 18:50:32 UTC 2020 i686 i686 i686 GNU/Linux
• Subsystem: fs, repl, linux

What is the bug?

Every time in the REPL:

> console.log(require('fs').realpathSync('~'));
Uncaught:
Error: ENOENT: no such file or directory, lstat '/home/raisinten/Desktop/universe/temp/project/~'
    at Object.realpathSync (node:fs:1753:7) {
  errno: -2,
  syscall: 'lstat',
  code: 'ENOENT',
  path: '/home/raisinten/Desktop/universe/temp/project/~'
}

What is the expected behavior?

> console.log(require('fs').realpathSync('~'));
/home/raisinten
undefined

[aduh95]

Shouldn't you use path.resolve for that kind of thing? fs.realpath only resolves ., .. and symbolic links according to the docs, ~ is neither of those.

[RaisinTen]

The docs also mention this after that:

This function behaves like realpath(3)

and realpath does resolve ~ correctly.

What feels weird about this is that it causes this error only in the REPL and works perfectly when run using node <file>.

I didn't try path.resolve with '~' yet.

[mscdex]

and realpath does resolve ~ correctly.

If you're checking that via your shell, you're using realpath(1), not realpath(3) directly. The latter does not support tilde expansion.

[addaleax]

Yes, ~ is a shell feature, not a file system one. Not supporting it is the right thing to do for Node.js.

[RaisinTen]

Thanks for the explanation! The reason why it worked when I ran it outside the REPL is that I passed in the path from the command line and the shell expanded it without my knowledge. 🤦