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I hang out on /r/dailyprogrammer sometimes - they had a challenge about these types of programs the other day and called them "quines." Check through some of these if you're interested, a few are 2 characters long (not sure how many bytes that is): http://www.reddit.com/r/dailyprogrammer/comments/2n11w8/2014...
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I'll be darned if I can find the URL to the story, but it is a brilliant application of giving the customer what they wanted. The short of it is that when you dropped back to the command line, early versions of DOS didn't clear the memory. That meant that the program really just went into stasis, but in practice it meant restarting; see, the program ran off the floppy then, so to save or load to another disk was tric…
Here you go: http://peetm.com/blog/?p=55
Thanks a mil for finding the link! I had a feeling I read the story from HN, and so it was:
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That's pretty amazing. I'm guessing DNA compactness is a survival advantage for viruses, and that's how this emerged? Is gene overlap common in other species?
I would think the opposite may be true, given that compressed information tends to be more sensitive to error, than uncompressed.
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Correct. A file will only be considered a binary executable if it has a proper header (ELF, Mach-O, etc) The default if no header and no shebang is to treat it like a shell script. In fact, an empty executable file has been used to implement /bin/true on some old systems. Why take the added cost of a disk seek when just the information in the inode will do?
>In fact, an empty executable file has been used to implement /bin/true on some old systems. Why take the added cost of a disk seek when just the information in the inode will do? why is this only on old systems? it seems very efficient.
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Correct. A file will only be considered a binary executable if it has a proper header (ELF, Mach-O, etc) The default if no header and no shebang is to treat it like a shell script. In fact, an empty executable file has been used to implement /bin/true on some old systems. Why take the added cost of a disk seek when just the information in the inode will do?
>In fact, an empty executable file has been used to implement /bin/true on some old systems. Why take the added cost of a disk seek when just the information in the inode will do? why is this only on old systems? it seems very efficient.
phiX174 virus - one of the world's smallest self-replicating programs :-) http://www.ncbi.nlm.nih.gov/nuccore/NC_001422.1 Enterobacteria phage phiX174 sensu lato, complete genome 5386 bp ss-DNA
Hehe funny that you mention phiX174 in the context of programming, that virus is amazing... Part of the reason phiX174 is so small is that it is "compressed" by having overlapping genes; in one area, three genes overlap in the same place! This is possible because there are 6 valid reading frames (direction and start point) for reading DNA: {forward or backward} x {address % 3 == 0, 1, or 2}. In college I actually got…
Get your genome compiler here: http://genomecompiler.com
Isn't this a quine, rather than a self-replicating program? A quine produces the source, and a self-replicating program should produce an executable - no? This seems to be a fallacy of equivocation.
$ ./smr >smr.out
$ diff smr smr.out