Re: Add SHELL_EXIT_CODE to psql

I've rebased and updated the patch to include documentation.

Regression tests have been moved to a separate patchfile because error
messages will vary by OS and configuration, so we probably can't do a
stable regression test, but having them handy at least demonstrates the
feature.

On Sun, Dec 4, 2022 at 12:35 AM Corey Huinker <corey(dot)huinker(at)gmail(dot)com>
wrote:

> Rebased. Still waiting on feedback before working on documentation.
>
> On Fri, Nov 4, 2022 at 5:23 AM Corey Huinker <corey(dot)huinker(at)gmail(dot)com>
> wrote:
>
>> Oops, that sample output was from a previous run, should have been:
>>
>> -- SHELL_EXIT_CODE is undefined
>> \echo :SHELL_EXIT_CODE
>> :SHELL_EXIT_CODE
>> -- bad \!
>> \! borp
>> sh: line 1: borp: command not found
>> \echo :SHELL_EXIT_CODE
>> 127
>> -- bad backtick
>> \set var `borp`
>> sh: line 1: borp: command not found
>> \echo :SHELL_EXIT_CODE
>> 127
>> -- good \!
>> \! true
>> \echo :SHELL_EXIT_CODE
>> 0
>> -- play with exit codes
>> \! exit 4
>> \echo :SHELL_EXIT_CODE
>> 4
>> \set var `exit 3`
>> \echo :SHELL_EXIT_CODE
>> 3
>>
>>
>> On Fri, Nov 4, 2022 at 5:08 AM Corey Huinker <corey(dot)huinker(at)gmail(dot)com>
>> wrote:
>>
>>>
>>> Over in
>>> https://www.postgresql.org/message-id/eaf326ad693e74eba068f33a7f518039@oss.nttdata.com Justin
>>> Pryzby suggested that psql might need the ability to capture the shell exit
>>> code.
>>>
>>> This is a POC patch that does that, but doesn't touch on the
>>> ON_ERROR_STOP stuff.
>>>
>>> I've added some very rudimentary tests, but haven't touched the
>>> documentation, because I strongly suspect that someone will suggest a
>>> better name for the variable.
>>>
>>> But basically, it works like this
>>>
>>> -- SHELL_EXIT_CODE is undefined
>>> \echo :SHELL_EXIT_CODE
>>> :SHELL_EXIT_CODE
>>> -- bad \!
>>> \! borp
>>> sh: line 1: borp: command not found
>>> \echo :SHELL_EXIT_CODE
>>> 32512
>>> -- bad backtick
>>> \set var `borp`
>>> sh: line 1: borp: command not found
>>> \echo :SHELL_EXIT_CODE
>>> 127
>>> -- good \!
>>> \! true
>>> \echo :SHELL_EXIT_CODE
>>> 0
>>> -- play with exit codes
>>> \! exit 4
>>> \echo :SHELL_EXIT_CODE
>>> 1024
>>> \set var `exit 3`
>>> \echo :SHELL_EXIT_CODE
>>> 3
>>>
>>>
>>> Feedback welcome.
>>>
>>