[Gllug] Tip: Scripting passwd

[James McGuigan]

I was trying to create a script to automate account creation via a web 
form, and this point had me stumped for a few hours, so I thought I'd 
share it with you.

The linux passwd command has a bug whereby it prompts for input before 
its ready to receive the data. This is due to a bug in an library 
function, so it also affects other passwd like commands (such as 
PureFTP's pure-pw command). AFAIK the bug only affects linux, and not 
*BSDs nor other UNIXs.

The solution is to add a short wait before sending each input. Google 
suggests using an expect script to do this, but it can also be done just 
as easy through the shell



user='james'; pass='secret';
(for i in 1 2; do sleep 0.1s; echo $pass; done;) | \
sudo -u root passwd $user



Note: this assumes you have setup the specific lines in the sudoers 
file. Its a bad security risk to allow user www-data to sudo to root.
However for non system accounts (like pureftp virtual accounts), you can 
create an ftpadmin account, give it write permissions on 
/etc/pure-ftp/pureftpd.passwd + /etc/pure-ftp/ (for pureftpd.passwd.tmp)

Then add this to the sudoers file (which is an acceptable risk):

Cmnd_Alias PUREDB_USERADD=/usr/bin/pure-pw useradd *
www-data   ALL=(ftpadmin)NOPASSWD:PUREDB_USERADD

-- 
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But for those who can, rules become nothing more than guidelines,
And live their lives governed not by rules but by reason.
      - James McGuigan

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