Read the entire contents of a file.
Asynchronously reads the entire contents of a file.
The function accepts the same options and has the same defaults as fs.readFile().
Synchronously reads the entire contents of a file.
The function accepts the same options and has the same defaults as fs.readFileSync().
can be replaced by an approach which addresses existence via `error` handling.
--flag flag           Flag. Default: 'r'.
Relative file paths are resolved relative to the current working directory.
File contents are written to stdout.