Fortran:using variable in call system command -

how use variable in call system command in fortran? example ,if want create multiple directories

test_1_1 test_1_2 , on till test_3_3

then should code be.

i trying following code can't seem figure out write in #### part.

integer  :: i,j ! = 1,3    j = 1,3  !   call system('mkdir folder ####)     enddo enddo 

character (len=8) :: test_name  i=1, 3    j=1, 3       write (test_name, '( "test_", i1, "_", i1 )' ) i, j       call system ( "mkdir " // test_name )    end end 

the format in example work long numbers single digits. if want larger values use i2.2 (for 2 digits, leading zero, if single digits), or i0, whatever number of digits needed.