Tranferring websites/users from one box to another

Tranferring websites/users from one box to another

When I was setting up my new web server, I had to copy the files from one
box to another.  But if you just do a tarball and ftp, you won’t get what you expect.
  Specifically, the permissions may be fuggered.  So here’s what I did to avoid
that problem.

It’s all about permissions and groups

Access to files and directories is determined by the permissions set upon
the directory tree.  The permissions are related to users and groups.  Users and
groups are defined by numbers as set in the password and group files.  When we do
"ls -l", we see the owner of the file, such as "www".  However,
that name is just for our benefit.  The underlying system actualy uses a number (a
user id, or UID) which is associated with that name.  To find out what number is
used, run vipw and look for www.  You’ll see something like this:

www:*:99:99::0:0:apache Daemon:/nonexistent:/sbin/nologin

This means that www has a UID (user id) of 99 and a default group id (GID) of 99.
  It’s those numbers which are important.  If we just copy files from one system
to another without first ensuring that the users on the new system have the same UID and
GID as the old system, we may find the results suprising at least.  And nasty at
worst.  For example, you might find that someone else already has the UID for www.
  That would allo them to read/write the files for which www previously had exclusive
access.  This can be quite a serious issue.  Be wary.


What I did was open vipw on both the source and destination boxes.  
Then I did a copy and paste from one box to the the other.  There, done.   Then
I did the same thing with /etc/group.  You do have to be careful when
doing this.  Make sure that the two systems are using the same password encryption
method.  You can usually tell that by looking at the passwords involved.  
Either they all start with $1 or they don’t.  Ask someone who knows more about
this.  Better still, if you know, please add your comments.

Copying the files from one box to the other

I chose tar and NFS to do this (see drive to drive backup and NFS
for preliminary details).  You could also just tar up the directories on one box, and
ftp them over, then extract them.  Or you could use rsync.

I exported the directory I wanted to backup.  Then I mounted that volume.  I did
an ls on both boxes to make sure I was seeing the correction user and group

Then I issued the following commands on the destination box:

# cd /path/to/source/nfs/mount/point
# tar -cvlf - . | ( cd /path/to/local/dest; tar xpf -)

Then I needed to merge the apache.conf files from one box to the other.  I took
everything after the default virtual hosts, changed the names for virtual hosts.  I
had serveral lines like this:


Which needed to look like this:


So I started vi, and issued this command:


And it was done.

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