$ cat vimrc
let g:indent_guides_enable_on_vim_startup = 0
let g:indent_guides_tab_guides = 0
let g:indent_guides_space_guides = 1
let g:indent_guides_soft_pattern = ' '

$ cat after/ftplugin/sh.vim 
setlocal noexpandtab
setlocal softtabstop=0
setlocal shiftwidth=4
setlocal tabstop=4

let b:indent_guides_enable_on_vim_startup=1
let b:indent_guides_tab_guides = 1  
let b:indent_guides_space_guides = 0
let b:indent_guides_soft_pattern = '\t'

$ cat vimrc
let g:indent_guides_enable_on_vim_startup = 1

$ cat after/ftplugin/sh.vim 
let b:indent_guides_enable_on_vim_startup=0