The canonical minimal test message in the C/Unix universe or any of the minimal programs that emit this message. Traditionally, the first program a C coder writes in a new environment is one that just prints "hello, world" to standard output (and indeed it is the first example program in K&R). Environments that generate an unreasonably large executable for this trivial test or which require a hairy compiler-linker invocation to generate it are considered bad (see X).