• Detect OS in Vimscript - Vi and Vim Stack Exchange
• has(xxx) 는 기능을 가지고 있는지 여부 체크이다. :help feature-list

if !exists("g:os")
    if has("win64") || has("win32") || has("win16")
        let g:os = "Windows"
    else
        let g:os = substitute(system('uname'), '\n', '', '')
    endif
endif
 
 
if has("gui_running")
    if g:os == "Darwin"
        set guifont=Fira\ Mono:h12
    elseif g:os == "Linux"
        set guifont=Fira\ Mono\ 10
    elseif g:os == "Windows"
        set guifont=Fira_Mono:h12:cANSI
    endif
endif