autoexec.vim

" automatically make script files executable when writing for the first time
function! NewScriptExec() abort
        " check if this is a new file which starts with a shebang
        if exists('s:new_file') && getline(1)[0:1] == '#!'
                " based on https://stackoverflow.com/a/57539332
                let l:file = expand('%')
                let l:old_perm = getfperm(l:file)
                " set the exec bit everywhere the read bit is set
                let l:new_perm = substitute(l:old_perm, '\v(r.)-', '\1x', 'g')
                if (l:old_perm != l:new_perm)
                        call setfperm(l:file, l:new_perm)
                endif
                unlet s:new_file
        endif
endfunction

augroup new_script_exec
        autocmd!
        autocmd BufNewFile * let s:new_file = 1
        autocmd BufWritePost * call NewScriptExec()
augroup END