Is there an alternative to GETCWD() in Fortran 2003-2008

As noted in the comments, you can make use of get_environment_variable which is standard Fortran (e.g. F2008 13.7.67). This example program queries the value of $PWD, which should contain the directory your shell is in when you invoked the executable.

program test
 implicit none
 character(len=128) :: pwd
 call get_environment_variable('PWD',pwd)
 print *, "The current working directory is: ",trim(pwd)
end program

And its output:

casey@convect code % pwd
/home/casey/code
casey@convect code % so/getpwd 
 The current working directory is: /home/casey/code

This is standard Fortran, but its portability will be limited to Unix and Unix-like shells that set this variable.

Another option while standard but ugly (in my opinion) would be to use execute_command_line to run a command that can output the working directory to a temporary file (e.g. pwd > /tmp/mypwd), then reading that file.

You can also use the ISO_C_Binding and call the corresponding C functions:

cwd.c:

#ifdef _WIN32
/* Windows */
#include <direct.h>
#define GETCWD _getcwd

#else
/* Unix */
#include <unistd.h>
#define GETCWD getcwd

#endif

void getCurrentWorkDir( char *str, int *stat )
{
  if ( GETCWD(str, sizeof(str)) == str ) {
    *stat = 0;
  } else {
    *stat = 1;
  }
}

test.F90:

program test
 use ISO_C_Binding, only: C_CHAR, C_INT
 interface
   subroutine getCurrentWorkDir(str, stat) bind(C, name="getCurrentWorkDir")
     use ISO_C_Binding, only: C_CHAR, C_INT
     character(kind=C_CHAR),intent(out) :: str(*)
     integer(C_INT),intent(out)         :: stat
    end subroutine
  end interface
  character(len=30)   :: str
  integer(C_INT)      :: stat

  str=''
  call getCurrentWorkDir(str, stat)
  print *, stat, trim(str)

end program

This code is valid for Windows and Unix-derivates (Linux, OSX, BSD, etc. )