Logging In and Out

If you do it in a text terminal, just type your user name at the prompt; you will be asked for your password; type it and you are in the system (if you did not do any mistake).

To log on in a X-windows terminal you will find a small window with a "Logging" Type your user name, and then your password; you will then go to an X-windows session.

To log out (exit) of a text teminal, type logout

To exit an X-windows session, use the mouse; click on the right buttom of it and choose the "Logout" or "exit" option.

If you want to access the system from outside (or some machine in the system remotely from another machine) you have several options:

1. ssh: secure shell, allows you to access a (remote) computer with security (the connection will be encrypted, and thus difficult to break). Just to

       ssh remote-computer
   

   If you are outside the School of Maths sytem, then the only computer you can acess by this way is telnet.math.tifr.res.in

   You can also execute commands with something like

      ssh remote-computer command-to-be-executed
   

2. rsh: remote shell, to log on in a remote computer with a command like

       rsh remote-computer
   

   Or execute a command with

       rsh remote-computer command-to-be-executed
   

   The difference between ssh and rsh is that the latter does not encrypt the data, so important things like password and other commands can (in principle) be read by an outside machine.
3. telnet: similar to the two commands above except that you can only access a system, there is no provision for executing commands in a remote machine (well, you can do it after you are logged on in the remote machine). The command is similar

      telnet remote-computer
   

   and the connection is not encrypted.

Some times the system will complain when you try to log out, with a message of the type There are stopped jobs and will not exit you from your session. In that case, you can try one of the following things:

1. Type jobs; the output is of the following form:

       [1]+ Stopped    less /etc/services
   

   Then you can call the job by doing

       fg %1
   

   and finish it. Log out after that. Or you could kill the job with

       kill %1
   

   or

       kill -9 %1
   

   and then log out.
2. Type

       kill -9 -1
   

   The disadvantage of this option is that it will kill any job that you are running. For example, if you left some long computation running it will be finished.

If you have problems to log out of a session that you started with ssh or rsh just type

   ~.

   Ctrl-]