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Full Discussion: Log Out SSH User in Bash
Top Forums Shell Programming and Scripting Log Out SSH User in Bash Post 302814793 by FreddoT on Thursday 30th of May 2013 08:19:58 AM
Old 05-30-2013
Wrench Log Out SSH User in Bash
So, I've been writing a system to allow users temporary access onto a system.

Essentially, there's a web server with a PHP script, the PHP script takes a Username & Password from a webform, and passes it to a script, createusr.sh.

The script looks something like this:

Code:
pass=$(perl -e 'print crypt($ARGV[0], "password")' $2)
sudo /usr/sbin/useradd $1 -s /bin/bash -p $pass -d /home/onlineusers/$1 -m
sudo /bin/chmod 700 /home/onlineusers/$1
sleep 1800
sudo /usr/sbin/userdel -f $1
sudo /bin/rm -rf /home/onlineusers/$1

Basically it creates a user, using the passed parameters, and force creates their home directory. It then makes that directory only accessible to said user, before sleeping for half an hour.

After that time it deletes the user and their home directory. But I have one problem. If the user is still logged on at that point, then the user deletion has no effect, as the user can still work.

At the moment, I am thinking of using:

Code:
pgrep -t <user's tty>

and then killing the bash, but I'm not sure how I can get the TTY of a user logged in through SSH?

Maybe somehow "grep" with "w" might do it, but not if the username contains something like "load" which is featured elsewhere in the output from "w".

Besides this, is there any way that I can send a message to a logged in user, saying something like "5 minutes left"?

Code:
write

seems like a possibility, but I'm not sure exactly how this would be implemented.
Last edited by FreddoT; 05-30-2013 at 09:27 AM..
 

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LEARN ABOUT POSIX

userdel

userdel(1M)                                               System Administration Commands                                               userdel(1M)

NAME

       userdel - delete a user's login from the system

SYNOPSIS

       userdel [-r] login

DESCRIPTION

       The  userdel  utility  deletes a user account from the system and makes the appropriate account-related changes to the system file and file
       system.

OPTIONS

       The following options are supported:

       -r       Remove the user's home directory from the system. This directory must exist. The files and directories under  the  home  directory
                will no longer be accessible following successful execution of the command.

OPERANDS

       The following operands are supported:

       login    An existing login name to be deleted.

EXIT STATUS

       The following exit values are returned:

       0        Successful completion.

       2        Invalid command syntax. A usage message for the userdel command is displayed.

       6        The account to be removed does not exist.

       8        The account to be removed is in use.

       10       Cannot update the /etc/group or /etc/user_attr file but the login is removed from the /etc/passwd file.

       12       Cannot remove or otherwise modify the home directory.

FILES

       /etc/passwd             system password file

       /etc/shadow             system file contain users' encrypted passwords and related information

       /etc/group              system file containing group definitions

       /etc/user_attr          system file containing additional user attributes

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE         |      ATTRIBUTE VALUE        |
       +-----------------------------+-----------------------------+
       |Availability                 |SUNWcsu                      |
       +-----------------------------+-----------------------------+

SEE ALSO

       auths(1),  passwd(1),  profiles(1),  roles(1),  users(1B),  groupadd(1M), groupdel(1M), groupmod(1M), logins(1M), roleadd(1M), rolemod(1M),
       useradd(1M), userdel(1M), usermod(1M), passwd(4), prof_attr(4), user_attr(4), attributes(5)

NOTES

       The userdel utility only deletes an account definition that is in the local /etc/group, /etc/passwd, /etc/shadow, and /etc/user_attr  file.
       file. If a network name service such as NIS or NIS+ is being used to supplement the local /etc/passwd file with additional entries, userdel
       cannot change information supplied by the network name service.

SunOS 5.10                                                          8 Sep 1999                                                         userdel(1M)
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