[NTLUG:Discuss] Catching exit code in a pipe?

[David Stanaway]

On 4/22/2010 11:28 PM, Patrick R. Michaud wrote:
> On Thu, Apr 22, 2010 at 10:11:55PM -0500, David Stanaway wrote:
>   
>> I have a backup script that includes:
>>
>> su -c "pg_dumpall | gzip -9 > backup/db.out.gz" -l postgres
>>
>> $? gets the most recent pipelined command exit, and catches the gzip
>> exit code which is always 0.
>>
>> I don't want to create an intermediate file uncompressed.
>>
>> Does anyone have an idea how I can do this in bash without getting too
>> creative with subshells and signal handlers?
>>     
> Perhaps...?
>
>   su -c "set -o pipefail; pg_dumpall | gzip -9 > backup/db.out.gz" -l postgres
>
> The "pipefail" option in bash(1) causes the pipeline to 
> return the exit code of the last failing command in the 
> pipeline.  So in the above, since the gzip always exits with zero,
> the returned exit code will come from the pg_dumpall command.
>
> Pm
>   

Thanks.

Thats perfect.

I may end up doing a hot backup of PG since there is less overhead with
that.

Thoughts? (Probably more a Q for the postgres list).

What are folkes doing here for backing up their PG databases with their
enterprise backup software?