Update.sh for linux users

[kendalf]

I know its pretty basic but I'm new to linux and git. Can someone help me convert the default update.bat into bash? I'm very confused by windows batch scripts.

environment.bat:

@echo off

set DIR=%~dp0system

set PATH=%DIR%\git\bin;%DIR%\python;%DIR%\python\Scripts;%PATH%
set PY_LIBS=%DIR%\python\Scripts\Lib;%DIR%\python\Scripts\Lib\site-packages
set PY_PIP=%DIR%\python\Scripts
set SKIP_VENV=1
set PIP_INSTALLER_LOCATION=%DIR%\python\get-pip.py
set TRANSFORMERS_CACHE=%DIR%\transformers-cache

update.bat:

@echo off

call environment.bat

git -C "%~dp0webui" pull 2>NUL
if %ERRORLEVEL% == 0 goto :done

git -C "%~dp0webui" reset --hard
git -C "%~dp0webui" pull

:done
pause

[Jeamorg]

Please use git pull to update