On 8/8/10 10:59 PM, "John R Pierce" pierce@hogranch.com wrote:

On 08/08/10 10:47 PM, Dotan Cohen wrote:

...

I have a Debian machine with four users that I plan on migrating to CentOS. As per Debian habits the UIDs start with 1000.

Is it enough to reuse the Debian /etc/shadow and /etc/passwd files over? Or will I need to configure some other things? I had considered just creating four new users starting from UID 500 then chown -R -ing the user's home directories, but I find that invasive and possibly error prone (maybe there are files that are not owned by them).

All advice appreciated. Thanks.

I'd compare the passwd files, noting the predefined system accounts. when I copy over /etc/passwd entries, I generally cut/paste them, not just copy the whole file. of course, the same entries for /etc/shadow

That and be careful of different hash algorithms being used.... (Found out the hard way when migrating users from an OpenSuSE box to CentOS....)

On Mon, Aug 09, 2010, Keith Roberts wrote:

On Mon, 9 Aug 2010, Gary Greene wrote:

...

To: CentOS list centos@centos.org From: Gary Greene ggreene@minervanetworks.com Subject: Re: [CentOS] Moving users from Debian-based distro to CentOS

On 8/8/10 10:59 PM, "John R Pierce" pierce@hogranch.com wrote:

...

On 08/08/10 10:47 PM, Dotan Cohen wrote:

...

I have a Debian machine with four users that I plan on migrating to CentOS. As per Debian habits the UIDs start with 1000.

Is it enough to reuse the Debian /etc/shadow and /etc/passwd files over? Or will I need to configure some other things? I had considered just creating four new users starting from UID 500 then chown -R -ing the user's home directories, but I find that invasive and possibly error prone (maybe there are files that are not owned by them).

what about using the `find` command, and piggy-back the chown command on that?

`pinfo find`

I find that it's fairly easy to migrate users from the old system to the new by creating rsync modules for each user pointing to the user's $HOME directory, then using rsync to copy everything to the user's directory to the new system.

This does not require having the uid/gid the same on the two systems, only that the user and group names be consistent. Here are a couple of sample rsyncd.conf entries for this:

[bill_upd] uid = bill gid = csys read only = false path = /home/bill comment = /home/bill use chroot = yes # only allow internal network hosts allow = 192.168.253.0/24 hosts deny = * list = no

[john_upd] uid = john gid = users read only = false path = /home/john comment = /home/john use chroot = yes # only allow internal network hosts allow = 192.168.253.0/24 hosts deny = * list = no

Then a fairly simple loop on the source machine can copy/sync each user's data from the old machine to the new one:

#!/bin/bash for user in bill john; do rsync -varP ~$user/ dstmachine::${user}_upd/ done

The rsync command takes care of the user/group mappings, and is very efficient. One can make an initial run to get the bulk of each user's files to the new machine, then do a final rsync just before the cut-over adding ``--delete'' to the rsync command to get rid of any files deleted from the old machine since the initial run.

We have used this to migrate ISP mail servers with thousands of user's $HOME directories containing Maildir mail stores with minimal down time. In this case, we created all the user accounts on the new machine so their $HOME directories existed, then did the rsync copies after switching the DNS for the mail servers to point to the new machine. There was a fairly short period in which users would see only new mail that arrived until their Maildir folders had been completely copied. On a machine with about 8,000 e-mail users, and gigabytes of data, it took a bit more than an hour to rsync all the user's accounts.

Bill

On Mon, 9 Aug 2010, John R Pierce wrote:

To: CentOS mailing list centos@centos.org From: John R Pierce pierce@hogranch.com Subject: Re: [CentOS] Moving users from Debian-based distro to CentOS

On 08/08/10 10:47 PM, Dotan Cohen wrote:

...

I have a Debian machine with four users that I plan on migrating to CentOS. As per Debian habits the UIDs start with 1000.

Is it enough to reuse the Debian /etc/shadow and /etc/passwd files over? Or will I need to configure some other things? I had considered just creating four new users starting from UID 500 then chown -R -ing the user's home directories, but I find that invasive and possibly error prone (maybe there are files that are not owned by them).

All advice appreciated. Thanks.

why not use useradd with the -u uid option so they match?

don't forget groups, btw. -g, -G, and create the groups with the same GID's.

Yes, that's the easiest way if there are only a few users on the system. The numeric UID's and GID's will still be on each users files and directories they own. So it makes sense to just create the user accounts with those UID's and GID's.

From my Auto Linux Installer script:

# -------------------------------------------------- # # Create test user account for rodney.

echo "Creating new user account for rodney" echo "Adding rodney to audio group" echo

useradd \ --comment 'User test account' \ --uid 505 \ --gid users \ --groups audio \ -M \ rodney

# Create login password for rodney. lusermod -P 'qazwsxe' rodney

# -------------------------------------------------- #

Kind Regards,

Keith Roberts

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