Using the catch command
The catch construct is used to prevent errors from aborting a script. The catch construct is a method of isolating errors and allowing you to determine how to proceed. This allows you to present the end user with a customized notification, as opposed to a system-defined error message, which may have no meaning to the user.
In the event an error condition exists, the catch command returns a non-zero integer value corresponding to the Tcl return code. Tcl provides four exceptional return codes. A return value of 1 (TCL_ERROR) indicates that an error has occurred and the value is stored in the result. A return of 2 (TCL_RETURN) is generated by the return command. A return of 3 (TCL_BREAK) is generated by the break command. ...
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