Able to make it works on windows machine as well for PATCH_SUPEE-5344_CE_1.8.0.0_v1-2015-02-10-08-10-38.sh.

Problem was: CURRENT_DIR=$PWD_BIN/ (line 60) and the value of $PWD_BIN is defined in same file PWD_BIN=which pwd (line 35) as which doesn't wok on windows so we will need to replace this value.

1. Open bash
2. Your current directory should be the root of magento.
3. Run command 'pwd'
4. It will give the out path of your current directory: Check screenshot

5. Copy this path and edit file, on line 67 replace:

   CURRENT_DIR=$PWD_BIN/ to CURRENT_DIR=/d/xampp/htdocs/magento/

Run patch with same commnd sh PATCH_SUPEE-5344_CE_1.8.0.0_v1-2015-02-10-08-10-38.sh

Note: Make sure you replace '/d/xampp/htdocs/magento/' with your directory root.

and it will work like a charm!!