
In Tk, we classify some of the variables as special variables and they have a predefined usage/functionality. The list of special variables is listed below.
| Sr.No. | Special Variable & Description | 
|---|---|
| 1 | tk_library Used for setting the location of standard Tk libraries.  | 
| 2 | tk_patchLevel Refers to the current patch level of the Tk interpreter.  | 
| 3 | tk_strictMotif When non-zero, Tk tries to adhere to Motif look-and-feel as closely as possible.  | 
| 4 | tk_version Displays the Tk version.  | 
The above special variables have their special meanings for the Tk interpreter.
Lets see the examples for special variables.
#!/usr/bin/wish puts $tk_version
When you run the program, you will get a similar output as shown below.
8.5
#!/usr/bin/wish puts $tk_library
When you run the program, you will get a similar output as shown below.
/Library/Frameworks/Tk.framework/Versions/8.6/Resources/Scripts
#!/usr/bin/wish puts $tk_patchLevel
When you run the program, you will get a similar output as shown below.
8.6.1
#!/usr/bin/wish puts $tk_strictMotif
When you run the program, you will get a similar output as shown below.
0