Editing /etc/passwd to disable password not working

[Santanu Chatterjee]

On Thu, Mar 1, 2012 at 4:13 PM, Ken Adams <adams.ken.j at gmail.com> wrote:
> On Thu, 2012-03-01 at 14:56 +0530, Santanu Chatterjee wrote:
>> Hello Everybody,
>>
>> I tried to disable the password of an account on my home ubuntu 11.04
>> box, by blanking the 2nd field of the corresponding user line in
>> /etc/passwd and /etc/shadow file. However, whenever I try to login to
>> the user account I am still being asked for the password and just
>> pressing 'enter' is not working.
>>
>> Is there something else that I should be doing? IIRC, I have tried
>> this some time back in probably ubuntu 8.10 (or maybe some lower
>> version) and it used to work.
>>
>> Thanks and regards,
>> Santanu
>>
>
> If you use the following the account will stay in place but be inactive.
>
> sudo passwd --lock [LOGIN]
>
> If you wish to activate the account again then use...
>
> sudo passwd --unlock [LOGIN]
>
> This will put activate the account with the original password.
>
> man passwd is your friend

Yes, its as you said. But this seems to be betraying me! Even "passwd
--delete [LOGIN]" does not render the account passwordless as apparent
from the manual. The commands you mentioned work, but I could do the
same thing using "sudo vipw" and "sudo vipw -s" to directly edit the
passwd and shadow files, and that works.

I think there something else in play here. Any ideas? I can't think of
any right now. If someone can provide a command that _will_ make an
account passwordless, then I could do this: Make a checksum of the etc
directory. Then give the command. Do the checksum again (using
something like Tripwire). That would help me figure out what was
changed by that command. But unless I have the command that does what
I want, there is no point is doing this.

But one thing is for sure, I _could_ make an account passwordless in
some previous ubuntu version (and other distros) by just removing the
password field in shadow/passwd files. ("sudo passwd --delete" seems
to be doing the same thing.)

-Santanu