>>807
inquireを使えば何とかならないかな。

program nurupo
logical :: opened
character(len=6) :: string
open(10,file="test10")
i=10
do
inquire(unit=i,opened=opened)
if(.not.opened) then
write(string,'("test",i2)') i
open(io,file=string)
write(*,'(i2," opened")') i
exit
endif
i=i+1
enddo
end program nurupo