shell - awk's END block behaviour on HP-UX

Question

Why does awk 'END{print}' file return an empty string?

I've checked the file and it does not end with empty line.

I'm on HP-UX.

Answer 1

From The GNU Awk guide - 7.1.4.2 Input/Output from BEGIN and END Rules

Traditionally, due largely to implementation issues, $0 and NF were undefined inside an END rule. The POSIX standard specifies that NF is available in an END rule. It contains the number of fields from the last input record. Most probably due to an oversight, the standard does not say that $0 is also preserved, although logically one would think that it should be. In fact, all of BWK awk, mawk, and gawk preserve the value of $0 for use in END rules. Be aware, however, that some other implementations and many older versions of Unix awk do not.

So, in general, END now contains the last $0, whereas in your [old] awk version it does not.

For example, my GNU Awk does work in the "new" way:

$ awk --version
GNU Awk 4.1.0, API: 1.0
$ seq 10 | awk 'END {print}'
10