in reply to Re^2: Linux::usermod - user name ... already exists
in thread Linux::usermod - user name ... already exists

Hello again mldvx4,

I was thinking exactly like this. That your script will do something like that.

Well an alternative solution would be to remove the user Linux::usermod->del(username); (I assume the module removes the user from all groups) and after that create a new user Linux::usermod->add(username, password, uid, gid, comment, home, shell); with the updated name. That could be a workaround (assuming there are no errors on this one as well). Not to forget you can assign the user to the desired groups 

@users = qw(user1 user2 user3);
Linux::usermod->grpadd(groupname, gid, "@users")

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. But again this is just theory I have not tested it so I do not know if there is a bug in all these commands.

Let us know at the end what solution you came up with. BR / Thanos

Seeking for Perl wisdom...on the process of learning...not there...yet!

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Re^4: Linux::usermod - user name ... already exists
by mldvx4 (Hermit) on Mar 20, 2019 at 06:17 UTC

    Thanks. I gave Linux::usermod->del(username); a try and see that it leaves the groups in /etc/group and /etc/shadow untouched instead of removing / modifying them as needed. I took a look at the source for Linux::usermod and it's over my skill level to dig in and form a patch, at least in a timely manner.

    I'll look into several options now but it may take some time.

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Re^4: Linux::usermod - user name ... already exists
by mldvx4 (Hermit) on Mar 20, 2019 at 14:20 UTC

    It looks like this is the distilled version of what I will try. The validation of the two variables takes place earlier in another function. 

    $ENV{'PATH'}=q(/sbin:/bin:/usr/sbin:/usr/bin);

my ($um,$gm);

qx/usermod --login $newname --home $newname $oldname/;
$um = $?;
if ($um==0) {
    qx/groupmod --new-name $newname $oldname/;
    $gm = $?;
}

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    Ideas or corrections?

    No output is produced, so I don't try to capture any. And the home directory gets reassigned and renamed elsewhere, too, since I have a little non-standard home directory arrangement for those groups.

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      Since you're setting a restricted PATH, are you running this under taint mode? If so, are $newname and $oldname user input? If yes, I would strongly recommend against putting them in a shell command like this (even though I assume you had to untaint them first). I'd suggest at the very least using system in the list form with more than one argument, e.g.:

      system('usermod','--login',$newname,'--home',$newname,$oldname)
    ==0 or die "usermod failed, \$?=$?";
system('groupmod','--new-name',$newname,$oldname)
    ==0 or die "groupmod failed, \$?=$?";

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      I wrote more on the topic of avoiding the shell here.

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        It runs under taint mode. As mentioned earlier in the thread, the script does sanitization and validation of the strings earlier on long before they get sent to the shell scripts. I would avoid using the system programs directly if possible, but Linux::usermod is missing the functions needed to proerly rename an account belonging to several groups.

        Could you please explain the advantages or differences between system() in list form and qx/ / in practice? I'm only interested in tracking if the action failed or succeeded and wish to suppress anything sent to stdin or stdout.

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      If you don't need the output, use system instead of qx. It returns the exit code directly, so no need to use $?.
      map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]
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