Re: confusing archive_command example - Mailing list pgsql-docs

Josh Kupershmidt wrote:
> Hi,
> On the page:
> http://www.postgresql.org/docs/current/interactive/continuous-archiving.html#BACKUP-ARCHIVING-WAL
>
> an example archive_command of:
> archive_command = 'cp -i %p /mnt/server/archivedir/%f </dev/null'
>
> is given. Then, a few lines later, an example archive command of:
> archive_command = 'test ! -f .../%f && cp %p .../%f'
>
> is given. I think this second command would be more clear if it used
> "/mnt/server/archivedir/" instead of "...", to tie in with the
> previous archive_command. It took me a minute to figure out that the
> three dots were supposed to be an ellipsis instead of a typo for the
> parent directory "..".

I agree our use of cp -i </dev/null is a little too fancy not to be
explained in the docs, so I have done so with the attached, applied
patch.

As far as "...", those are used to show only the important changes in
the string, which I think is the right approach, but I did change the
line so the dots are not right up against slashes:

    archive_command = 'test ! -f ... %f && cp %p ... %f'

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com
Index: doc/src/sgml/backup.sgml
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      directory).
      It is advisable to test your proposed archive command to ensure that it
      indeed does not overwrite an existing file, <emphasis>and that it returns
!     nonzero status in this case</>.  We have found that <literal>cp -i</> does
!     this correctly on some platforms but not others.  If the chosen command
!     does not itself handle this case correctly, you should add a command
!     to test for existence of the archive file.  For example, something
!     like:
  <programlisting>
  archive_command = 'test ! -f .../%f && cp %p .../%f'
  </programlisting>
--- 604,615 ----
      directory).
      It is advisable to test your proposed archive command to ensure that it
      indeed does not overwrite an existing file, <emphasis>and that it returns
!     nonzero status in this case</>.  On many Unix platforms, <command>cp
!     -i</> causes copy to prompt before overwriting a file, and
!     <literal>< /dev/null</> causes the prompt (and overwriting) to
!     fail.  If your platform does not support this behavior, you should
!     add a command to test for the existence of the archive file.  For
!     example, something like:
  <programlisting>
  archive_command = 'test ! -f .../%f && cp %p .../%f'
  </programlisting>