osx man page for unset

unset(n)						       Tcl Built-In Commands							  unset(n)

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NAME
       unset - Delete variables

SYNOPSIS
       unset ?-nocomplain? ?--? ?name name name ...?
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DESCRIPTION
       This  command removes one or more variables.  Each name is a variable name, specified in any of the ways acceptable to the set command.	If
       a name refers to an element of an array then that element is removed without affecting the rest of the array.  If a  name  consists  of	an
       array name with no parenthesized index, then the entire array is deleted.  The unset command returns an empty string as result.	If -nocom-
       plain is specified as the first argument, any possible errors are suppressed.  The option may not be abbreviated, in order to  disambiguate
       it  from possible variable names.  The option -- indicates the end of the options, and should be used if you wish to remove a variable with
       the same name as any of the options.  If an error occurs, any variables after the named one causing the error are not  deleted.	 An  error
       can  occur  when the named variable does not exist, or the name refers to an array element but the variable is a scalar, or the name refers
       to a variable in a non-existent namespace.

EXAMPLE
       Create an array containing a mapping from some numbers to their squares and remove the array elements for non-prime numbers:
	      array set squares {
		  1 1	 6 36
		  2 4	 7 49
		  3 9	 8 64
		  4 16	 9 81
		  5 25	10 100
	      }

	      puts "The squares are:"
	      parray squares

	      unset squares(1) squares(4) squares(6)
	      unset squares(8) squares(9) squares(10)

	      puts "The prime squares are:"
	      parray squares

SEE ALSO
       set(n), trace(n), upvar(n)

KEYWORDS
       remove, variable

Tcl									8.4								  unset(n)