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- “Hello, World!” 748 answers
Is it possible to write (pack) a shorter than 145 bytes version of a program with "Hello world" (plus new line) output if the length of the program is measured as a number of bytes in program's ELF (x86) representation? Reduction technique in mind is described here:
Please reply with providing a code example. Note, 1 says "Hi world" and  returns 42 instead of an output, hence I assume current solution to be 142 + (len("Hello") - len("Hi")) which is 145.
Limits of ELF: syntactically a program translated into ELF is determined by its interpreter (libc), which is a combination of:
- Target architecture (Generic, AMD64, ARM, IA-32, MIPS, etc.)
- OS kernel (which communicates with implementation of ELF interpreter and often is itself packed into an ELF binary)
From TIS spec. 1.2
There is one valid program interpreter for programs conforming to the ELF specification for the Intel architecture: /usr/lib/libc.so.1
In theory - all clear - multiple combinations times version differences (Arch, OS) are possible. In practice - because standard is less strict than any BNF for CFG or other finer (smaller) formal language - there can be implementation differences (options) including shorter length of the program.
On one hand, because ELF is not that precise (one naturally expects) it is much more difficult to do code-golf with it. Hence a "Hello world\n" program is expected to be by default in TIS ELF 1.2, x86 (Generic Intel), Linux 2.6.(20+). On the other hand having a shorter ELF that runs e.g. on *BSD seems like an extremely valuable knowledge to me!
For example ELF64 (latest draft) is much more interesting incl. the differences with ELF(x86). So, please share a solution that can be accepted with correction to specific configuration.
Motivation: It is the practical part that is interesting for me and code-golf is a very nice way to show how tricky it is to come up with any machine- (or even byte) code in general and why ELF does apparently such a good job (in my understanding). Thus a golf solution is not only cool per say but also can provide a practical knowledge of unexpected interpretation differences of ELF (if an alternative combination is given).