30 Mar
2025
30 Mar
'25
2 p.m.
Doug,
It turns out there wasn't enough context and we both got
confused. The "requirement" is that
awk '{ print }' ...
look to the lexer / grammer as if it had been "{ print }\n".
There is no requirement that input "text" files behave as if a
final newline is always there.
Thanks,
Arnold
Douglas McIlroy <douglas.mcilroy(a)dartmouth.edu> wrote:
"The
requirement that awk add a trailing <newline> to the program argument
text is to simplify the grammar, making it match a text file in form."
This should no more be a *requirement* for awk than globbing should have
been a requirement for MS-DOS apps. A widespread principle deserves a
widespread answer. If it is a requirement on awk, then for interoperability
it should be made a requirement on all programs that handle text files,
especially editors.
The way to do that, of course, would be to redefine text file to allow a
non-newline as the last character. Ugh.
Not warning perpetuates travesties like "awk END{print NR}' " giving a
different
answer than "wc -l".
I agree that awk does the kind thing by supplying the final newline. But
it should recognize that this is non-standard behavior and warn in the
interest of discouraging the proliferation of garbage.
Postel's so-called "robustness principle" is in play here. "Be
conservative
in what you send, be liberal in what you accept" would better read,
"Send conservatively; receive amply but grudgingly".
Doug