[ILUG] Question about transferring system

[kevin lyda]

On Wed, Apr 14, 2004 at 01:50:43AM +0100, bobb wrote:
> Michael Treacy hath declared on Tuesday the 13 day of April 2004  :-:
> > >Could he not just add the users and groups change the uid and gids in the
> > >/etc/passwd and /etc/groups to suit the old system and mount the old drives
> > >/home as /home ??
> > 
> > Only problem is, I have a few hundred users, 'cos its a server in a school 
> > lab! I'd rather not have to add them all again if I didn't have to....
>  
> Yeah... you will probably get away with just copying over the old 
> password files... however you should take care doing it, there may
> be new important system accounts in the defailt password files in 9
> Things might go a little screwy if they are missing or there are
> incorrect entries....

most adduser tools create user accounts with uids greater then a certain
number (on redhat it's > 500).  so a bit of perl could rip out all the
user accounts from the old passwd/group/gshadow files.  something like:

    # assumes old disk is mounted in /mnt and that user uids
    # start at 500
    open(P, "</mnt/etc/passwd");
    open(NP, ">/root/new.passwd");
    while (<P>) {
        @l = split(/:/);
        if ($l[2] >= 500) {
            print NP $_;
            $gid{$l[3]} = 1;
            $login{$l[0]} = 1;
        }
    }
    close(P);  close(NP);

    open(G, "</mnt/etc/group");
    open(NG, ">/root/new.group");
    while (<G>) {
        @l = split(/:/);
        if ($gid{$l[2]} == 1) {
            print NG $_;
            $group{$l[0]} = 1;
        }
    }
    close(G);  close(NG);

    open(G, "</mnt/etc/gshadow");
    open(NG, ">/root/new.gshadow");
    while (<G>) {
        @l = split(/:/);
        if ($group{$l[0]} == 1) {
            print NG $_;
        }
    }
    close(G);  close(NG);

    open(S, "</mnt/etc/shadow");
    open(NS, ">/root/new.shadow");
    while (<S>) {
        @l = split(/:/);
        if ($login{$l[0]} == 1) {
            print NS $_;
        }
    }
    close(S);  close(NS);

then just append the new.* files to their respective files in /etc.

kevin

-- 
kevin at ie.suberic.net  ~  Would you put on your resume that 3,000 people
                         died due to your failure while you were in charge?

                         So why is George Bush?