IDL shows inverted images after use of DEFROI

In case that the display of images is inverted every time you show it, it is very likely
that one system variable was changed.
Please try to set

IDL>device, set_graphics_function=3


This happens most likely if you type CTRL-C within the program DEFROI

vmware stops ctrl and shift key from working

If you encounter that vmware stops ctrl and shift keys from working in linux then do not panic!

The solution is to run setxkbmap in a shell.
This command brings back the shift and ctrl keys.

automatic ssh login to remote without a password

If you wish to login to a remote machine without giving the password every time, use following sequence:

1) generate on your LOCAL machine a key pair with: ssh-keygen -t rsa (don't type in any password, just keep hitting enter)
2)file transfer the (local) PUBLIC key ~/.ssh/id_rsa.pub to the machine you which to automatically login to and append it to the (remote) file ~/.ssh/authorized_keys on your remote machine
3)make sure the (remote) authorized_keys is not read or modifiable by group or others my doing (remote) chmod 700 ~/.ssh/authorized_keys
4)make sure the ~/.ssh directory on the REMOTE machine is not read or modifiable by group or others my doing (remote) chmod 700 ~/.ssh
5)You may need to enable empty password authentication (need root access) on the REMOTE machine in the config file sshd_config. Make "permitemptypasswords yes". Restart SSH Daemon on REMOTE.

That's it

If you still can not log in without password then check the priorities of your home directory.
You can as well change temporarily in the file /etc/ssh/sshd_config
If this does not help, change the following option on the remote sshd config:

#LogLevel INFO
to
LogLevel DEBUG

...and of course restart the sshd daemon.
Then you see why it is still not working in the /var/log/messages file.

automatic ssh login to remote without a password

no copy/paste between vncviewer and shell

In case that there is no copy/paste functionality between a vnc session and
your linux shell then check the if the following command is running on the
computer where the vncserver is running:
>vncconfig -display :? -iconic -nowin &
the ? has to be replaced with the display of the vncsession.
It is handy to store this line already in the ~/.vnc/xstartup script

fglrx:firegl_init_module *ERROR* firegl_stub_register failed

If you get this error message while inserting the module fglrx then just unload
the modules radeon and drm. This solves the problem

ssh login takes much time

If the ssh login to a machine needs much time (more than 10 seconds) then put the line
UseDNS no to the sshd_config on the machine you want to connect to and restart the daemon.

If it is still slow then check if the /etc/hosts file contains the proc that you were about to connect from.
The point is that you do not only need to resolve the name of the proc that you want to connect to but also the name of the proc you connect from.

This really works and the login time should be below one second.