On Tue, Nov 12, 2024 at 05:14:50AM +0000, fxkl4...@protonmail.com wrote: > On Mon, 11 Nov 2024, David Wright wrote: > > > On Tue 12 Nov 2024 at 02:47:21 (+0000), fxkl4...@protonmail.com wrote: > >> i down loaded super_program.appimage > >> on the command line i type ./super_program.appimage > >> how does my debian powered device know what to do > > > > It looks at the file signature, or "magic number", in the first few > > bytes of the file. For example, type: > > > > $ hexdump -C /bin/cat | head -n 1 > > 00000000 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 > > |.ELF............| > > $ > > > > and the 7f 45 4c 46 sequence means Executable and Linkable Format. > > OTOH, in: > > > > $ hexdump -C /bin/firefox | head -n 1 > > 00000000 23 21 2f 62 69 6e 2f 73 68 0a 0a 46 49 52 45 46 > > |#!/bin/sh..FIREF| > > $ > > > > the first two bytes, 23 21, indicate that the file should be passed > > to the program whose name immediately follows, ie /bin/sh, which is > > normally the dash shell in Debian. > > > > See https://en.wikipedia.org/wiki/List_of_file_signatures for > > loads more magic numbers. > > > > Cheers, > > David. > > > > i don't see anything in that about appimage
There are more of those patterns. Try "file": file super_proram.appimage pattern pattern patternsss ...what does it tell you? Perhaps the binfmt_misc entry in the Wikipedia gives you a starting point on how the Linux kernel decides what to do when it is told to "run" (aka "exec") a file. Cheers [1] https://en.wikipedia.org/wiki/Binfmt_misc -- t
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