I am getting the error: Tcl Error no display name and no DISPLAY environment variable,
when I am running python tkinter scripts on my system.

Can anyone explain and help?

Hi,

The DISPLAY is indeed an environment variable, you can reference it firstly from a shell (like BASH or CSH) and also from tcl scripts.

type "env" in a shell and you can see the environment variables defined in your login environment.

type "echo $DISPLAY" in a shell to see the current value of the variable. Chances are it is empty.

If you set it to ":0" then it should just use the display of your machine. Otherwise you can attempt to pipe the screen output to another machine by "machineip:0" that will only work if they have permitted the connection.

Hopefully that is the only problem you need to fix.

Are you running in X windows?
Your DISPLAY should normally be set if you're running
X.

My scripts are running at login and my default runlevel is 3.
Then I am issuing command 'startx' to start X. But when it is
entering the X then the script is showing error.

Well, you can't run the scripts before X has started if
it is looking for an X session.

What are the scripts for?

this are python tkinter GUI scripts.