You may install it with pip :

pip install RPi.GPIO

Not sure if this is helpful, but under the latest copy of Raspbian I was able to install RPi.GPIO directly from the main repositories using apt-get as follows:

sudo apt-get update
sudo apt-get -y install python-rpi.gpio

If you're running Python 3 (idle3 on the command line) instead of Python 2 (python on the command line) you need to install the RPi.GPIO library with this command instead:

sudo apt-get -y install python3-rpi.gpio

I was able to fix the issue by installing RPi.gpio using pip3. Type the following commands:

export CFLAGS=-fcommon

pip3 install RPi.GPIO

Source: https://www.raspberrypi.org/forums/viewtopic.php?t=289084

this is reprint of an answer by karel at this location https://askubuntu.com/questions/621134/gpio-on-raspberry-pi

In the terminal type:

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install python-pip python-dev
sudo pip install RPi.GPIO  

The raspberry-gpio-python examples are worth reading. In the Inputs example there is this code snippet:

while GPIO.input(channel) == GPIO.LOW:
    time.sleep(0.01)

It waits 10 ms to give CPU a chance to do other things.

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)  # set board mode to Broadcom

GPIO.setup(17, GPIO.OUT)  # set up pin 17
GPIO.setup(18, GPIO.OUT)  # set up pin 18

GPIO.output(17, 1)  # turn on pin 17
GPIO.output(18, 1)  # turn on pin 18

from here.