.vimrc

function! PGrep(pattern, ...)
    let pattern = a:pattern

    if a:0 == 0
        let ext = '*'
    else
        let ext = a:1
    endif

    let proj_path = system("echo $PROJ_PATH | tr -d '\n'")

    let search_path = proj_path . "/**/*." . ext

    :execute "vimgrep /" . pattern . "/j " search_path | :copen
endfunction

command! -nargs=* PGrep :call PGrep(<f-args>)