Can't find a usable init.tcl in the following directories

转到python 的安装目录，在命令行中执行：python lib/idlelib/idle.py

可以看到：
D:\Python26>python lib/idlelib/idle.py
Traceback (most recent call last):
  File "lib/idlelib/idle.py", line 21, in <module>
    idlelib.PyShell.main()
  File "D:\Python26\lib\idlelib\PyShell.py", line 1386, in main
    root = Tk(className="Idle")
  File "D:\Python26\lib\lib-tk\Tkinter.py", line 1643, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
_tkinter.TclError: Can't find a usable init.tcl in the following directories:
    {D:\usr\ov\bin} D:/Python26/lib/tcl8.5 D:/lib/tcl8.5 D:/lib/tcl8.5 D:/library D:/library D:/tcl8.5.2/library
所以修改系统变量TCL_LIBRARY 为：D:\Python26\tcl\tcl8.5 就可以了

Project Navigator - Error "tcl Error: Can't find a usable init.tcl in the following directories: /Tcl/dist/export/lib/tcl8.4"

Description
Invoking a Tcl shell with the Xilinx directory in the path causes the following error:

"% tcl Error: Can't find a usable init.tcl in the following directories: $Xilinx/env/TOS/Tcl/dist/export/lib/tcl8.4 $Xilinx/env/TOS/Tcl/dist/export/lib/tcl8.4

This probably means that Tcl wasn't installed properly.

while executing "error $msg" (procedure "tclInit" line 42) invoked from within "tclInit"

while initializing application (Tcl_AppInit?)"

解决方案
Thiserror can occur if the system in use has multiple Tcl shells.

To run Tcl commands on Xilinx projects, use the Xilinx Tcl shell (xtclsh).

NOTE: "xtclsh" will find the "init.tcl" from the correct place in the Xilinx install.

Using Xtclsh might limit xtclsh to only Xilinx ISE software use.

For customers who want to run both ISE toolsand other Tcl-based programs (e.g., 'tkdiff'), a work-around is to use two separate terminal windows.