io_commandline Subroutine

  subroutine io_commandline(prog, dryrun, post_proc_flag, seedname)
    !================================================
    !
    !! Parse the commandline
    !
    !================================================

    implicit none

    character(len=:), allocatable, intent(in) :: prog
    !! Name of the calling program
    logical, intent(out) :: dryrun, post_proc_flag
    !! Have we been asked for a dryrun
    character(len=:), allocatable, intent(inout)  :: seedname

    integer :: num_arg, loop
    character(len=50), allocatable :: ctemp(:)
    logical :: print_help, print_version
    character(len=10) :: help_flag(3), version_flag(3), dryrun_flag(3)

    help_flag(1) = '-h    '
    help_flag(2) = '-help '
    help_flag(3) = '--help '

    version_flag(1) = '-v    '
    version_flag(2) = '-version '
    version_flag(3) = '--version '

    dryrun_flag(1) = '-d    '
    dryrun_flag(2) = '-dryrun '
    dryrun_flag(3) = '--dryrun '

    post_proc_flag = .false.
    print_help = .false.
    print_version = .false.
    dryrun = .false.

    num_arg = command_argument_count()
    allocate (ctemp(num_arg))
    do loop = 1, num_arg
      call get_command_argument(loop, ctemp(loop))
    end do

    if (num_arg == 0) then
      ! program called without any argument
      print_help = .true.
    elseif (num_arg == 1) then
      ! program called with one argument
      if (any(index(ctemp(1), help_flag(:)) > 0)) then
        print_help = .true.
      elseif (any(index(ctemp(1), version_flag(:)) > 0)) then
        print_version = .true.
      elseif ((ctemp(1) (1:1) == '-')) then
        !catch any other flag. Note seedname can't start with '-'
        print_help = .true.
      else  ! must be the seedname
        seedname = trim(ctemp(1))
      end if
    else ! not 2 - as mpi call might add commands to argument list
      if (any(index(ctemp(1), help_flag(:)) > 0)) then
        print_help = .true.
      elseif (any(index(ctemp(1), version_flag(:)) > 0)) then
        print_version = .true.
      elseif (any(index(ctemp(1), dryrun_flag(:)) > 0)) then
        dryrun = .true.
        seedname = trim(ctemp(2))
        if (seedname(1:1) == '-') print_help = .true.
      elseif (index(ctemp(1), '-pp') > 0) then
        post_proc_flag = .true.
        seedname = trim(ctemp(2))
        if (seedname(1:1) == '-') print_help = .true.
      else  ! must be the seedname
        seedname = trim(ctemp(1))
        if (seedname(1:1) == '-') print_help = .true.
      end if
    end if

    if (print_help) then
      if (prog == 'wannier90') then
        write (6, '(a)') 'Wannier90: The Maximally Localised Wannier Function Code'
        write (6, '(a)') 'http://www.wannier.org'
        write (6, '(a)') ' Usage:'
        write (6, '(a)') '  wannier90.x <seedname>               : Runs file <seedname>.win'
        write (6, '(a)') '  wannier90.x -pp <seedname>           : Write postprocessing files for <seedname>.win'
        write (6, '(a)') '  wannier90.x [-d|--dryrun] <seedname> : Perform a dryrun calculation on files <seedname>.win'
        write (6, '(a)') '  wannier90.x [-v|--version]           : print version information'
        write (6, '(a)') '  wannier90.x [-h|--help]              : print this help message'
      elseif (prog == 'postw90') then
        write (6, '(a)') 'postw90: Post-processing for the Wannier90 code'
        write (6, '(a)') 'http://www.wannier.org'
        write (6, '(a)') ' Usage:'
        write (6, '(a)') '  First run wannier90.x then'
        write (6, '(a)') '  postw90.x <seedname>               : Runs file <seedname>.win'
        write (6, '(a)') '  postw90.x [-d|--dryrun] <seedname> : Perform a dryrun calculation on files <seedname>.win'
        write (6, '(a)') '  postw90.x [-v|--version]           : print version information'
        write (6, '(a)') '  postw90.x [-h|--help]              : print this help message'
      end if
      stop
    end if

    if (print_version) then
      if (prog == 'wannier90') then
        write (6, '(a,a)') 'Wannier90: ', trim(w90_version)
      elseif (prog == 'postw90') then
        write (6, '(a,a)') 'Postw90: ', trim(w90_version)
      end if
      stop
    end if

    ! If on the command line the whole seedname.win was passed, I strip the last ".win"
    if (len(trim(seedname)) .ge. 5) then
      if (seedname(len(trim(seedname)) - 4 + 1:) .eq. ".win") then
        seedname = seedname(:len(trim(seedname)) - 4)
      end if
    end if

  end subroutine io_commandline