> The problem here is that although sed was written in "C" and we have a "C compiler" on our system, the definition of what exactly constitutes "C" has changed.

> The problem here is that although sed was written in "C" and we have a "C compiler" on our system, the definition of what exactly constitutes "C" has changed. The modern compiler no longer accepts the same language as the V7 compiler. Standards provide solid points of reference in this mess: 1989 ANSI/ISO C is not going to change. Specific compilers come and go, but the language defined by those documents (one ANSI, one ISO) is unchanging and, more importantly, well-understood such that C compiler implementers both feel the need to implement it correctly and understand how. > Looking forward, the sed from a current system is likely to be similarly rotted when you try to use it on a machine 40 years from now. I think it's likely the language won't rot the same way, due to the standardization I mentioned, but the OS interfaces beyond POSIX or similar might rot.