How to redirect the raw_input to stderr and not stdout?

问题

I want to redirect the stdout to a file. But This will affect the raw_input. I need to redirect the output of raw_input to stderr instead of stdout. How can I do that?

回答1:

Redirect stdout to stderr temporarily, then restore.

import sys

old_raw_input = raw_input
def raw_input(*args):
    old_stdout = sys.stdout
    try:
        sys.stdout = sys.stderr
        return old_raw_input(*args)
    finally:
        sys.stdout = old_stdout

回答2:

The only problem with raw_input is that it prints the prompt to stdout. Instead of trying to intercept that, why not just print the prompt yourself, and call raw_input with no prompt, which prints nothing to stdout?

def my_input(prompt=None):
    if prompt:
        sys.stderr.write(str(prompt))
    return raw_input()

And if you want to replace raw_input with this:

import __builtin__
def raw_input(prompt=None):
    if prompt:
        sys.stderr.write(str(prompt))
    return __builtin__.raw_input()

(For more info, see the docs on __builtin__, the module that raw_input and other built-in functions are stored in. You usually don't have to import it, but there's nothing in the docs that guarantees that, so it's better to be safe…)

In Python 3.2+, the module is named builtins instead of __builtin__. (Of course 3.x doesn't have raw_input in the first place, it's been renamed input, but the same idea could be used there.)

回答3:

Use getpass

import getpass

value=getpass.getpass("Enter Name: ")
print(value)

This will print the content value to stdout and Enter Name: to stderr.

Tested and works with python 2.7 and 3.6.

来源：https://stackoverflow.com/questions/21202403/how-to-redirect-the-raw-input-to-stderr-and-not-stdout

标签

python

python-2.x