I'm asking for a way to create a zip without the .DS_Store or __MACOSX for less sophisticated Apple computer users who have to coexist with Windows users who cannot accept a zip with the .DS_Store and __MACOSX.
os x zip without resource forks
Alternatively, you could try Keka, which also has an option to exclude the .DS_store file. Open Keka, click on zip, and check Exclude Mac OS X resource forks and drop what you want to compress on the Keka window.
EDIT, after many downvotes: I was using this option for some time ago and I don't know where I learnt it, so I can't give you a better explanation. Chris Johnson's answer is correct, but I won't delete mine. As one comment says, it's more accurate to what OP is asking, as it compress without those files, instead of removing them from a compressed file. I find it easier to remember, too.
Archive Utility only creates a __MACOSX directory when you create an archive where at least one file contains metadata such as extended attributes, file flags, or a resource fork. The __MACOSX directory contains AppleDouble files whose filename starts with ._ that are used to store OS X-specific metadata. The zip command line utility discards metadata such as extended attributes, file flags, and resource forks, which also means that metadata such as tags is lost, and that aliases stop working, because the information in an alias file is stored in a resource fork.
Normally you can just discard the OS X-specific metadata, but to see what metadata files contain, you can use xattr -l. xattr also includes resource forks and file flags, because even though they are not actually stored as extended attributes, they can be accessed through the extended attributes interface. Both Archive Utility and the zip command line utility discard ACLs.
The file type/creator info, and any resource fork, are both lost when transferring the file to other OS without care. When using unix command line utils (cp, tar, gz, etc), whether these data are kept depends on which command you are using. Also, each version of OS X, Apple updates some command line tools so that they preserve these data.
Note that if you want to preserve resource fork, you must use the version supplied with the Mac 10.6.x, at /usr/bin. This means if you have installed GNU's version (from Fink or MacPorts), remember to start you command with full path /usr/bin/ if you still want resource fork.
For example, you can do tar cvf myfolder.tar myfolder. This will result a new file named tar cvf myfolder.tar. This file itself will have no resource fork. All the resources are embedded in the file. Now, move the tar file to a new dir, untar it by tar xvf myfolder.tar. The result dir's files will still have resource fork.
The resource fork is a fork or section of a file on Apple's classic Mac OS operating system, which was also carried over to the modern macOS for compatibility, used to store structured data along with the unstructured data stored within the data fork.
A resource fork stores information in a specific form, containing details such as icon bitmaps, the shapes of windows, definitions of menus and their contents, and application code (machine code). For example, a word processing file might store its text in the data fork, while storing any embedded images in the same file's resource fork. The resource fork is used mostly by executables, but every file is able to have a resource fork.
The resource fork is sometimes used to store the metadata of a file, although it can also be used for storing the actual data, as was the case with font files in the classic Mac operating systems. Note that the Macintosh file systems also have a separate area for metadata distinct from either the data or resource fork. Being part of the catalogue entry for the file, it is much faster to access this. However, the amount of data stored here is minimal, being just the creation and modification timestamps, the file type and creator codes, fork lengths, and the file name. Some files have only a resource fork. Classic 68k applications are one example, where even the executable code is contained in resources of type 'CODE'. Later PowerPC binaries store the executable code in the data fork.
As resource forks are supported only on the file systems HFS, HFS Plus, and APFS, they cannot be used on operating systems which use other file systems. At present, HFS is supported only by the Macintosh operating system, which means that only machines running Mac OS can use resource forks. Even in a Mac OS system, resource forks cannot be used if the Unix File System has been installed. In the HFS Plus file system, settings can be made to allow other forks in addition to the data and resource forks, to create a "multi-fork" application. However, as forks can make it difficult to exchange files with other operating systems, this feature is not in common use. Even in macOS, resource forks are seldom used anymore.
As the resource fork can be edited with a resource editor such as ResEdit, it can be used to localize and customize software. In addition, most resource editors allow visual editing of data. In macOS, it is possible to use resources when developing an application. However, if the application may need to be used in UFS, it is also possible to configure it so that the entire resource fork is moved to the data fork, using the Raw Resource File setting. The integrated development environments distributed for free by Apple Inc., which include MPW and Apple Developer's Tools, include a compiler called Rez. This uses a dedicated language, also called Rez, which can be used to create a resource fork by compiling source code. A decompiler, DeRez, which can be used to change a resource fork back into Rez code is also included.
In the structure of the resource fork, there is a piece of data called a "resource map" which stores the positions of resource data items. This can be used to allow random access to resource data based on the defined IDs and names. The resource fork can be thought of as consisting of essentially two objects, the resource map and the resource data itself, but in fact each data type is a hierarchical structure which stores multiple items of data. The format in which the information in the resource data is stored is defined based on the types of information, which are known as "resource types." Resource data often makes references to other types of data.
In macOS, forks are named file/..namedfork/forkname, e.g., the resource fork of the file IMG_0593.jpg is IMG_0593.jpg/..namedfork/rsrc. The ls command supports a -l@ option which lists a file's forks.
From the POSIX interface, the resource fork could be accessed as filename/..namedfork/rsrc or as filename/rsrc; the shorter form was deprecated in Mac OS X v10.4 and removed completely in Mac OS X v10.7.[3]
The smallest elements making up a resource fork are called data types. There are several data types. After a resource fork is accessed, its contents can be found by reading it in as appropriate for the data types defined in advance. Placing definitions inside the program stating how data is to be treated makes it possible to store resources called TMPL resources as well. Using this method increases the visibility of the data when viewed with a program such as ResEdit, making later editing simpler. As the Macintosh platform originated with Motorola-based processors (68k and PPC), the data is serialized to disk in big-endian format.
The type codes below, like the above datatypes, are used as type identifiers for more than resource forks themselves: they are used to identify file themselves, to describe data in the clipboard, and much more.
The complexity of programming with resource forks has led to compatibility problems when accessing other file systems via file sharing protocols such as AFP, SMB, NFS and FTP, when storing to non-HFS volumes, or when transmitting files to other systems in other ways (such as via email). The AFP protocol natively supports Resource Forks, and so resource forks are typically transmitted to these volumes as-is, and stored by the server transparently to clients. The SMB protocol supports a file metadata system similar to Macintosh forks known as Alternate Data Streams (ADSes hereafter). macOS did not support storing resource forks in ADSes on SMB volumes by default until Mac OS X v10.6. In previous versions of the OS, including upgraded versions of 10.6, this feature can be enabled with a param change or by creating a special file.[4]
Networked file sharing protocols such as NFSv3 and FTP do not have a concept of file metadata, and so there is no way to natively store resource forks. This is also true when writing to certain types of local file systems, including UFS, and on SMB volumes where Alternate Data Stream support is not enabled. In those cases, macOS stores metadata and resource forks using a technique called AppleDouble, in which the data fork is written as one file, and the resource fork and metadata are written as an entirely separate file preceded by a "._" naming convention. For example: ExampleFile.psd would contain the data fork, and ._ExampleFile.psd would contain the resource fork and metadata.
Compatibility problems can arise because macOS will handle storage of resource forks differently, depending on macOS version, settings, and file system type. For example, on an SMB network with a mixture of 10.5 and 10.6 clients. A freshly installed 10.6 client will look for and store resource forks on an SMB volume in ADSes, but the 10.5 client will (by default) ignore ADSes and use AppleDouble format to handle forks. If a fileserver supports both AFP and NFS, then clients using NFS will store files in AppleDouble format, whereas AFP users will stored the resource fork natively. In those cases, compatibility can sometimes be maintained by forcing clients to use, or not use, AppleDouble format.
Many fileservers providing AFP support do not natively support resource forks on their local file systems. In those cases the forks may be stored in special ways, such as specially named files, special directories, or even Alternate Data Streams. 2ff7e9595c
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