Re: fflush & close behavior not well-defined

[arnold]

Hi.

I had an epiphany last night as to what the issue is, but I'd
already shut down my laptop.

Gawk isn't at fault, nor is the C library. It's the bash version.
On Fedora 7:

$ bash --version
GNU bash, version 4.2.46(2)-release (x86_64-redhat-linux-gnu)

On Ubuntu 18.04:

$ bash --version
GNU bash, version 4.4.20(1)-release (x86_64-pc-linux-gnu)

Why does it matter?  Remember that the string that can be used for
pipelines can be any shell command. Gawk runs /bin/sh to execute the
command; the exit status that comes back *is that of the shell*, not
of the command it runs!

To wit, if we modify your one-line slightly by using exec:

$ cat x.awk
BEGIN { LINT = 1 }
BEGIN {print "hello" |& "exec cat"; print close("exec cat")}

On Fedora:

$ ./gawk -f x.awk
gawk: x.awk:2: warning: failure status (269) on two-way pipe close of `exec 
cat': Success
269

And now on Ubuntu:

$ ./gawk -f x.awk 
gawk: x.awk:2: warning: failure status (269) on two-way pipe close of `exec 
cat': Success
269

Ta da!

The previous 141 came from bash, where:

1. The exit status of the shell is the status of the last command it ran
2. If the command exited upon signal, the status is 128 + the signal number

I *knew* that that was going on somewhere!

Apparently Bash changed at some point, from passing up the unadulterated
wait(2) exit status, to working as just described.

I will see if I can adjust the test.

And WOW! Talk about dark corners...

Thanks,

Arnold

P.S. I can't seem to duplicate this issue directly at the command line...
Oh well.