4636584d5b
re: https://github.com/Unidata/netcdf-c/issues/1154 Inadvertently, the behavior of NC_DISKLESS with nc_create() was changed in release 4.6.1. Previously, the NC_WRITE flag needed to be explicitly used with NC_DISKLESS in order to cause the created file to be persisted to disk. Additional analyis indicated that the current NC_DISKLESS implementation was seriously flawed. This PR attempts to clean up and regularize the situation with respect to NC_DISKLESS control. One important aspect of diskless operation is that there are two different notions of write. 1. The file is read-write vs read-only when using the netcdf API. 2. The file is persisted or not to disk at nc_close(). Previously, these two were conflated. The rules now are as follows. 1. NC_DISKLESS + NC_WRITE means that the file is read/write using the netcdf API 2. NC_DISKLESS + NC_PERSIST means that the file is persisted to a disk file at nc_close. 3. NC_DISKLESS + NC_PERSIST + NC_WRITE means both 1 and 2. The NC_PERSIST flag is new and takes over the obsolete NC_MPIPOSIX flag. NC_MPIPOSIX is still defined, but is now an alias for the NC_MPIIO flag. It is also now the case that for netcdf-4, NC_DISKLESS is independent of NC_INMEMORY and in fact it is an error to specify both flags simultaneously. Finally, the MMAP code was fixed to use NC_PERSIST as well. Also marked MMAP as deprecated. Also added a test case to test various combinations of NC_DISKLESS, NC_PERSIST, and NC_WRITE. This PR affects a number of files and especially test cases that used NC_DISKLESS. Misc. Unrelated fixes 1. fixed some warnings in ncdump/dumplib.c
Unidata NetCDF
About
The Unidata network Common Data Form (netCDF) is an interface for scientific data access and a freely-distributed software library that provides an implementation of the interface. The netCDF library also defines a machine-independent format for representing scientific data. Together, the interface, library, and format support the creation, access, and sharing of scientific data. The current netCDF software provides C interfaces for applications and data. Separate software distributions available from Unidata provide Java, Fortran, Python, and C++ interfaces. They have been tested on various common platforms.
Properties
NetCDF files are self-describing, network-transparent, directly
accessible, and extendible. Self-describing means that a netCDF file
includes information about the data it contains. Network-transparent
means that a netCDF file is represented in a form that can be accessed
by computers with different ways of storing integers, characters, and
floating-point numbers. Direct-access means that a small subset of a
large dataset may be accessed efficiently, without first reading through
all the preceding data. Extendible means that data can be appended to
a netCDF dataset without copying it or redefining its structure.
Use
NetCDF is useful for supporting access to diverse kinds of scientific data in heterogeneous networking environments and for writing application software that does not depend on application-specific formats. For information about a variety of analysis and display packages that have been developed to analyze and display data in netCDF form, see
More information
For more information about netCDF, see
Latest releases
You can obtain a copy of the latest released version of netCDF software for various languages:
Copyright
Copyright and licensing information can be found here, as well as in the COPYRIGHT file accompanying the software
Installation
To install the netCDF-C software, please see the file INSTALL in the netCDF-C distribution, or the (usually more up-to-date) document:
Documentation
A language-independent User's Guide for netCDF, and some other language-specific user-level documents are available from:
- Language-independent User's Guide
- NetCDF-C Tutorial
- Fortran-90 User's Guide
- Fortran-77 User's Guide
- netCDF-Java/Common Data Model library
- netCDF4-python
A mailing list, netcdfgroup@unidata.ucar.edu, exists for discussion of the netCDF interface and announcements about netCDF bugs, fixes, and enhancements. For information about how to subscribe, see the URL
Feedback
We appreciate feedback from users of this package. Please send comments, suggestions, and bug reports to support-netcdf@unidata.ucar.edu.