Performing front-end backups
The Frontend backup function is intended to provide the capability to
perform an unattended, timed backup of your site.
The script performs one backup step and sends an HTTP 302 header to
force the client to advance to the next page, which performs the next step
and so forth. You will only see a message upon completion, should it be
successful or not. There are a few limitations, though:
It is NOT designed to be run from a normal web browser, but from
an unattended cron script, utilizing wget or cron as a means of
accessing the function.
The script is not capable of showing progress messages.
Normal web browsers tend to be "impatient". If a web page returns
a bunch of 302 headers pointing to itself, the web browser thinks that
the web server has had some sort of malfunction and stop bothering with
the page. It might also show some kind of "destination unreachable"
message. Remember, these browsers are meant to be used on web pages
which are supposed to show some content to a human. This behaviour is
normal. Most browsers will quit after they encounter the twentieth page
redirect response, which is bound to happen if you use the Slow
algorithm or have a large web site.
Command line utilities will give up on a page after it has been
redirected a number of times. For example, wget gives up after 20
redirects, curl after 50 redirects. Since JoomlaPack redirects once for
every step, it is advisable to configure your command line utility with
a large number of redirects; I believe 1000 will do for 99,9% of
sites.
Most hosts offer a CPanel of some kind. There has to be a section for
something like "CRON Jobs", "scheduled
tasks" and the like. The help screen in there describes how to
set up a scheduled job. One missing part for you would be the command to
issue. Simply putting the URL in there is not going to work. If you are on a
UNIX-style OS host (usually, a Linux host) you most probably have access to
a command line utility called wget. It's almost trivial to use:
wget --max-redirect=1000
"http://www.yoursite.com/index2.php?option=com_joomlapack&
view=backup&key=YourSecretKey&format=raw"
Of course, the line breaks are included for formatting clarity only.
You should not have a line break in your command line!
![[Important]](/images/stories/docimport48/important.png) | Important |
|---|
Do not miss the --max-redirect=1000 part of the
wget command! If you fail to include it, the backup
will not work with wget complaining that the maximum
number of redirections has been reached. This is normal behavior, it is
not a bug. |
![[Warning]](/images/stories/docimport48/warning.png) | Warning |
|---|
Do not forget the double quotation marks which surround the URL.
Otherwise the ampersands and other special characters will be interpreted
by your shell and cause the backup to fail. |
If you're unsure, check with your host. Sometimes you have to get from
them the full path to wget in order for CRON to work, thus turning the above
command line to something like:
/usr/bin/wget --max-redirect=1000
"http://www.yoursite.com/index2.php?option=com_joomlapack&
view=backup&key=YourSecretKey&format=raw"
Contact your host; they usually have a nifty help page for all this
stuff.
Optionaly, you can also include an extra parameter to the above URL,
&id=profile_id, where
profile_id is the numeric ID of the profile you
want to use for the backup. If you don't specify this parameter, the default
backup profile (ID=1) will be used. In this sense, the aforementioned URL
becomes:
/usr/bin/wget --max-redirect=1000
"http://www.yoursite.com/index2.php?option=com_joomlapack&
view=backup&key=YourSecretKey&format=raw&profile=profile_id"
wget is multi-platform command line utility
program which is not included with all operating systems. If your system
does not include the wget command, it can be
downloaded at this address: http://wget.addictivecode.org/FrequentlyAskedQuestions#download.
The wget homepage is here: http://www.gnu.org/software/wget/wget.html.
Please note that the option --max-redirect is available on
wget version 1.11 and above. At the time of this
writing this particular version was not available for the Windows
™operating system.
| Important |
|---|
Using a web browser (Internet Explorer, Firefox, ...) or
wget version 1.10 and earlier will most probably
result into an error message concerning the maximum redirections limit
being exceeded. This is not a bug. Most network
software will stop dealing with a web site after it has redirected the
request more than 20 times. This is a safety feature to avoid consuming
network resources on misconfigured web sites which have entered an
infinite redirection loop. JoomlaPack uses redirections creatively, to
force the continuation of the backup process without the need for
client-side scripting. It is possible, depending on site size, JoomlaPack
configuration and server setup, that it will exceed the limit of 20
redirections while performing a backup operation. |
