Where is the mime plugin file on mac and linux?

Question

I was just curious how the mime types were read / interpreted by local applications, including the browser. Are mime reading plugins embedded in every application or is there a special system folder in the OS to which the application belongs when interpreting the mime type?

The RFC uses chart symbols as references in determining which type of MIME:

(1) text message bodies in character sets other than US-ASCII

Although MDN , it looks like it uses the content-type , which you will find in things like HTML

Does something like content-type=image/jpeg or content-type=application/javascript use a UTF-8 char chart to determine its encodings (glyph), while something else does the logic to determine what these char glyphs should be interpreted?

OR does this mean that each type of content has its own special charchart (for example, utf-8 → js-8 ????), which does a glyphic conversion of the symbolic and logical interpretation of char to binary?

Why does this sound like charcharts and content-type, like average MIME? Where is the folder path for both Mac and Linux systems containing content type / interpretation charts?

Answer 1

They are mainly located in / usr / share / mime and / usr / share / mime-info, and linux and mac (almost the entire unix tree) do not correspond to extensions, but only the content, the extension is only for the convenience of the user.

Note: specific applications are located in "/ usr / share / mimelnk" (thanks to David C. Rankin)

(You can also try making a locate mime in the terminal for more information)

Answer 2

On macOS, you can use file --mime "/path/to/filename" to report the type of mime file.

The man page for file (see here ) sheds some light on what is happening under the hood, in front of me the type of search:

  file tests each argument in an attempt to classify it. There are three sets of tests, performed in this order: filesystem tests, magic tests, and language tests. The first test that succeeds causes the file type to be printed. The filesystem tests are based on examining the return from a stat(2) system call. The program checks to see if the file is empty, or if it's some sort of special file. Any known file types appropriate to the sys- tem you are running on (sockets, symbolic links, or named pipes (FIFOs) on those systems that implement them) are intuited if they are defined in the system header file <sys/stat.h>. The magic tests are used to check for files with data in particular fixed formats. The canonical example of this is a binary executable (compiled program) a.out file, whose format is defined in <elf.h>, <a.out.h> and possibly <exec.h> in the standard include directory. These files have a ``magic number'' stored in a particular place near the beginning of the file that tells the UNIX operating system that the file is a binary exe- cutable, and which of several types thereof. The concept of a ``magic'' has been applied by extension to data files. Any file with some invari- ant identifier at a small fixed offset into the file can usually be described in this way. The information identifying these files is read from the compiled magic file /usr/share/file/magic.mgc, or the files in the directory /usr/share/file/magic if the compiled file does not exist. If a file does not match any of the entries in the magic file, it is examined to see if it seems to be a text file. ASCII, ISO-8859-x, non- ISO 8-bit extended-ASCII character sets (such as those used on Macintosh and IBM PC systems), UTF-8-encoded Unicode, UTF-16-encoded Unicode, and EBCDIC character sets can be distinguished by the different ranges and sequences of bytes that constitute printable text in each set. If a file passes any of these tests, its character set is reported. ASCII, ISO-8859-x, UTF-8, and extended-ASCII files are identified as ``text'' because they will be mostly readable on nearly any terminal; UTF-16 and EBCDIC are only ``character data'' because, while they contain text, it is text that will require translation before it can be read. In addi- tion, file will attempt to determine other characteristics of text-type files. If the lines of a file are terminated by CR, CRLF, or NEL, instead of the Unix-standard LF, this will be reported. Files that con- tain embedded escape sequences or overstriking will also be identified. Once file has determined the character set used in a text-type file, it will attempt to determine in what language the file is written. The lan- guage tests look for particular strings (cf. <names.h>) that can appear anywhere in the first few blocks of a file. For example, the keyword .br indicates that the file is most likely a troff(1) input file, just as the keyword struct indicates a C program. These tests are less reliable than the previous two groups, so they are performed last. The language test routines also test for some miscellany (such as tar(1) archives). Any file that cannot be identified as having been written in any of the character sets listed above is simply said to be ``data''.