While we're being silly, here's a shell oneliner that outputs its own SHA1 hash[1]: A=shasum; C=echo; I='($C "A$s$A$X C$s$C$X I$s$Q$I$Q$X Q$s$k$Q$k$X k$s$Q$k$Q

While we're being silly, here's a shell oneliner that outputs its own SHA1 hash[1]: A=shasum; C=echo; I='($C "A$s$A$X C$s$C$X I$s$Q$I$Q$X Q$s$k$Q$k$X k$s$Q$k$Q$X X$s$Q$X$Q$X s$s$Q$s$Q$X $I" | $A)'; Q="'"; k='"'; X=';'; s='='; ($C "A$s$A$X C$s$C$X I$s$Q$I$Q$X Q$s$k$Q$k$X k$s$Q$k$Q$X X$s$Q$X$Q$X s$s$Q$s$Q$X $I" | $A) Note that this is not in any way opening its own source code as a file or through shell magic or something like that, in fact it's not looking at its own code at all. It really generates its own hash computationally out of itself, and would work the same if this was a compiled C program computing (not containing!) the hash of its own source code, even if the source code was thrown away. This may seem impossible at first, but it's really just a funny variant of a quine (a program that prints its own source). http://www.madore.org/~david/computers/quine.html http://www.madore.org/~david/computers/quine.html came up with the idea and explains the concept. [1] You could trivially change it to output its SHA2 hash instead (which just wasn't as common at the time I did this), but then you'd loose the particularly "nice" hash. That property is entirely unrelated to outputting its own hash, and done the same as the commit hashes linked here.