Introduction

When wgrib2 opens a file, the file may be marked as persistent or transient. If a file is marked as transient, wgrib2 will close the file as part of its normal "finalize" procedure. If a file is marked as persistent, the file will closed when the system terminates the program. If you run the wgrib2 utility, it makes no difference who closes the files. However, when you use the C/Fortran API, it makes a major difference. When you write C/Fortran programs that calls the wgrib2 API, you may want to use the same file thousands of times. It is better to open the file once rather than thousands of times. The -persistent option marks an already open file as persistent. The -transient option marks an already open file as transient. When opening a file, the default is to mark the file as persistent.

Usage

-persistent FILE
  FILE must be already opened