freebsd stable - Apr 2011 - conf/156396: Make 220.backup-pkgdb cd(1) and backup only the package database.

"J. Hellenthal" <jhell@DataIX.net> writes:

[...]
> @@ -33,7 +33,8 @@
>  
>  	new_bak_file=`mktemp ${bak_file}-XXXXX`
>  
> -	if tar -cjf "${new_bak_file}" "$pkg_dbdir"; then
> +	cd $pkg_dbdir/..
> +	if tar -cjf "${new_bak_file}" "$(basename
$pkg_dbdir)"; then
Why not use `-s' (substitution) option of bsdtar(1)?

  if tar -cjf "${new_bak_file}" -s "|$pkg_dbdir||"
"$pkg_dbdir"; then

$(basename $pkg_dbdir) is technically wrong as PKG_DBDIR points not to
/var/db but to /var/db/pkg by default and is not guaranteed to contain
`pkg' at the tail, e.g.

  PKG_DBDIR is /foo, so /var/backups/pkgdb.bak.tbz-XXX has foo/ prefix
  PKG_DBDIR is /blah/bar, so /var/backups/pkgdb.bak.tbz-YYY has bar/ prefix

It only adds one more hoop to jump through when restoring from backup, e.g.

  tar xf /var/backups/pkgdb.bak.tbz-XXX --strip-components 1 -C $PKG_DBDIR ...

On Fri, Apr 15, 2011 at 12:57:15PM +0400, Pan Tsu wrote:
>"J. Hellenthal" <jhell@DataIX.net> writes:
>
>[...]
>> @@ -33,7 +33,8 @@
>>  
>>  	new_bak_file=`mktemp ${bak_file}-XXXXX`
>>  
>> -	if tar -cjf "${new_bak_file}" "$pkg_dbdir"; then
>> +	cd $pkg_dbdir/..
>> +	if tar -cjf "${new_bak_file}" "$(basename
$pkg_dbdir)"; then
>
>Why not use `-s' (substitution) option of bsdtar(1)?
>
>  if tar -cjf "${new_bak_file}" -s "|$pkg_dbdir||"
"$pkg_dbdir"; then
>
>$(basename $pkg_dbdir) is technically wrong as PKG_DBDIR points not to
>/var/db but to /var/db/pkg by default and is not guaranteed to contain
>`pkg' at the tail, e.g.
I think you misunderstood how this works. You should test it...

With a pkg_dbdir pointing to /var/db/pkg basename strips off
"/var/db/".
The cd(1) you notice before that line makes sure your in the directory
just before the actual pkg_dbdir so therefore calling tar on $(basename
$pkg_dbdir) tar's up only the actual name of the 'pkg' directory and
not
the path before it.

I suppose this could also be achieved simply by:

tar -C $pkg_dbdir/.. -cjf "${new_bak_file}" "$(basename
$pkg_dbdir)"

which is equivalent to:

tar -C /var/db/pkg/.. -cvjf /tmp/foo.tbz `basename /var/db/pkg`

'-v' added for show.

But I don't think the author is willing to take any improvements and has
the wrong impression of why the '/..' is where it is and how that
suffices for the same motive behind archiving a direct path.


PS: The PR says this was committed... It was not AFAIK.


-- 

 Regards,

 J. Hellenthal

-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 522 bytes
Desc: not available
Url :
http://lists.freebsd.org/pipermail/freebsd-stable/attachments/20110415/51039393/attachment.pgp