To run gitignore.io from your command line you need an active internet connection and an environment function. You need to add a function to your environment that lets you access the gitignore.io API.
Create a Command Line Prompt Script If you have installed msysgit), create gi.cmd with content below. And copy it to C:\Program Files\Git\cmd\gi.cmd, assuming msysgit was installed to c:\Program Files\Git. Make sure that C:\Program Files\Git\cmd is added to the environment variable path.
@rem Do not use "echo off" to not affect any child calls.
@setlocal
@rem Get the abolute path to the parent directory, which is assumed to be the
@rem Git installation root.
@for /F "delims=" %%I in ("%~dp0..") do @set git_install_root=%%~fI
@for /F "delims=" %%I in ("%~dp0..") do @set git_mingw_root=%%~fI\mingw
@if not exist "%git_mingw_root%" @set git_mingw_root=%git_install_root%\mingw64
@set PATH=%git_install_root%\bin;%git_mingw_root%\bin;%PATH%
@if not exist "%HOME%" @set HOME=%HOMEDRIVE%%HOMEPATH%
@if not exist "%HOME%" @set HOME=%USERPROFILE%
@curl.exe -L -s https://www.toptal.com/developers/gitignore/api/%*