---
name: "itkvars"
section: "n"
platform: "macos"
package: "tcl"
version: "152"
release: "macOS 26.5"
platforms: ["macos"]
url: "https://new.carta.tech/itkvars/n"
---

# itkvars(n)

variables used by \[incr Tk\]

## NAME

itkvars - variables used by \[incr Tk\]

## DESCRIPTION

The following global variables are created and managed automatically by the **\[incr Tk\]** library.  Except where noted below, these variables should normally be treated as read-only by application-specific code and by users.

- **itk::library**

  When an interpreter is created, **\[incr Tk\]** initializes this variable to hold the name of a directory containing the system library of **\[incr Tk\]** scripts.  The initial value of **itk::library** is set from the ITK\_LIBRARY environment variable if it exists, or from a compiled-in value otherwise.

  When **\[incr Tk\]** is added to an interpreter, it executes the script "`init.itk`" in this directory.  This script, in turn, looks for other script files with the name "`init.`*xxx*". Mega-widget libraries will be automatically initialized if they install a script named "`init.`*xxx*" in this directory, where "*xxx*" is the name of the mega-widget library. For example, the **\[incr Widgets\]** library installs the script "`init.iwidgets`" in this directory. This script establishes the "iwidgets" namespace, and sets up autoloading for all **\[incr Widgets\]** commands.

## KEYWORDS

itcl, itk, variables