osStdout

os.Stdout is the standard output stream provided by Go's standard library. It is exposed as the exported variable Stdout in the os package and represents the process’s primary destination for textual output. In code, it is a pointer to an os.File, specifically a *os.File, that wraps the underlying file descriptor for standard output.

On POSIX systems, os.Stdout corresponds to file descriptor 1. On Windows, it maps to the system’s standard output handle. The underlying type, *os.File, offers methods such as Write and WriteString, and can be used with I/O utilities that accept an io.Writer, such as fmt.Fprintln, fmt.Fprintf, or bufio.Writer. By default, writing to os.Stdout appears in the program’s terminal or shell where the program was invoked, and can be redirected by the shell to a file or another process.

Common usage patterns include writing program output directly to os.Stdout, or via fmt or bufio wrappers for line-buffered or formatted output. It is typical to do fmt.Fprintln(os.Stdout, "message") or to pass os.Stdout to functions that accept an io.Writer. If buffered output is desired, developers often wrap os.Stdout with a buffered writer (e.g., bufio.NewWriter(os.Stdout)) to improve performance for many small writes.

Note that os.Stdout is a real file handle for the process. Closing it is generally discouraged, as it prevents further output and may disrupt the shell or other components. For testing or redirection, it is common to substitute a different writer or use interprocess communication rather than closing the global Stdout.