.. _kill-command-label:

=================
KILL Command
=================

Material prepared from `M Programming Book`_ (Page 78) [WALTERS1997]_ and `GT.M Programmer's Guide`_

**KILL** [:bool] *var1[,var2][,(ex1,ex2)]*

Description
###########

KILL, at its most basic level, deletes variables specified in its arguments.

KILL is optionally used with an exclusive list, or a conditional, or on multiple arguments. Additionally, it may be used with no arguments to delete all local variables.

KILLing an undefined variable has no effect.

Arguments
#########

**-var1,var2,...**

Specifies the local variable(s) to be deleted.

*Example*::

	SET A=1,B=2
	KILL A,B
	SET C=3
	KILL C
	*Local variables A and B (and then C) will be deleted, and will return undefined if referenced*

**-:bool**

An optional true/false expression. If true, the kill command will execute. If false, nothing happens.

*Example*::

	SET A=1,B=1
	KILL:A=1 B
	KILL:A=2 A
	*A=1 evaluates true, so B is deleted. Then, A=2 evaluates false, so A is not deleted*

**-ex1,ex2**

Optionally, an exclusive list (list of variables in parentheses) can be provided. Those variables in the exclusion list will be preserved, while every other variable is deleted. In the event of a variable appearing in the exclusive list and argument list (ex. KILL (A,B),A), its exclusive property is ignored, and it is KILLed.

*Example*::

	SET A=1,B=2,C=3
	KILL (A,B)
	*A and B are kept, and the remaining variable C is deleted*

Related
#######

*  :ref:`new-command-label`


References
##########

`KILL page at GT.M Programmer's Guide`_


.. _M Programming book: http://books.google.com/books?id=jo8_Mtmp30kC&printsec=frontcover&dq=M+Programming&hl=en&sa=X&ei=2mktT--GHajw0gHnkKWUCw&ved=0CDIQ6AEwAA#v=onepage&q=M%20Programming&f=false
.. _GT.M Programmer's Guide: http://tinco.pair.com/bhaskar/gtm/doc/books/pg/UNIX_manual/index.html
.. _KILL page at GT.M Programmer's Guide: http://tinco.pair.com/bhaskar/gtm/doc/books/pg/UNIX_manual/ch06s15.html