smallest-hello-rs

Smallest 64-bit Hello, World! in Rust in the World¹. Follow up blog post available here. Using compiler/linker flags and a simple python script, I managed to get the size down from 276792 bytes (270KiB) to a mere 149 bytes. The binary is called hello and checked into git. For comparison, the smallest Windows Hello World! in Rust is 1536 bytes. There's still a LOT more space in the ELF header, as most of it is ignored.

Some very helpful resources:

• https://mainisusuallyafunction.blogspot.com/2015/01/151-byte-static-linux-binary-in-rust.html
• https://dev.to/szymongib/single-syscall-hello-world-in-rust-part-2-4jj4
• https://os.phil-opp.com/freestanding-rust-binary/
• https://darkcoding.net/software/a-very-small-rust-binary-indeed/
• https://www.muppetlabs.com/~breadbox/software/tiny/teensy.html
• https://www.muppetlabs.com/~breadbox/software/tiny/revisit.html
• https://gcc.gnu.org/onlinedocs/gcc/Link-Options.html
• http://timelessname.com/elfbin/
• https://in4k.github.io/wiki/linux
• https://jacobgw.com/blog/zig/low-level/2021/03/15/elf-linux.html

Ideas

• Put the whole message into one buffer, makes one less syscall
• Mark all the editable fields with a special character
• Go for a beer?

Footnotes

1. Most probably, the only other one I was able to find was 151 bytes. ↩