BUG #10053: Re: COPY (...) TO 'file' doesn't create file

The following bug has been logged on the website:

Bug reference: 10053
Logged by: PFudd
Email address: postgresql(dot)org(at)ch(dot)pkts(dot)ca
PostgreSQL version: 9.2.8
Operating system: CentOS 6.5
Description:

Apparently I'm *partially* a doofus.

The "copy" command does its work on the server, not the
client. Use "\copy" for the client, without quotes or
trailing semicolon:

# psql -h 1.2.3.4 -U username -c "\\copy (select * from
history) to /tmp/foo.txt" dbname

I did check on the server in the /tmp directory, but no file
was created. This is probably a postgres permissions issue,
but I can see no way to show or change the relevant
permission to write to the filesystem; more googling
required.

I'm only *partially* a doofus because the original command
should generate an error message if it's not actually
opening and writing to the specified file on the server.
Let that be my bug report! :-)

Thanks!

> In psql, this command works:
> # copy (select * from history) to STDOUT;
> It prints 957 lines to stdout.
>
> However, if I do:
> # copy (select * from history) to '/tmp/foo.txt';
> it prints
> COPY 957
> but doesn't create the file /tmp/foo.txt.
>
> If the filename is changed to 'foo.txt' it says:
> ERROR: relative path not allowed for COPY to file
> so we know that it's at least looking at the filename critically.
>
> If the filename is changed to /tmp/foo.txt without the single quotes, it
says:
> ERROR: syntax error at or near "/"
> as expected.
>
> It doesn't matter if I'm doing this as a regular user or as the root
user.
>
> Using strace, it can be seen there was no attempt to stat or open that
filename for writing:
>
> # env PGPASSWORD=password strace -fo/tmp/strace.log psql -h 1.2.3.4 -U
username -c "copy (select * from history where num=5) to '/tmp/foo.txt'"
analyzer_local
>
> # cat /tmp/foo.txt
> cat: /tmp/foo.txt: No such file or directory
>
> # grep -c foo.txt /tmp/strace.log
> 0
>
> This was tried with psql 9.2.8 and psql 9.1.13, connecting to a server
running 9.2.4.