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Top Forums UNIX for Advanced & Expert Users $$number in the shell or shellscript Post 302562954 by kvmreddy on Sunday 9th of October 2011 06:35:35 AM
Old 10-09-2011
CPU & Memory

Using $$variablename is useful in indirect reference
I'm finding it hard to put into words, but consider this example:

Suppose you want to find last command line argument, how can you find it?

Code:
[root@localhost ~]# echo $#
3
[root@localhost ~]# echo $3
file3

But with indirect reference you can directly get it.

Code:
[root@localhost ~]# eval echo "\$$#"
file3

Newer bash also support's following format.

Code:
[root@localhost ~]# echo "${!#}"
file3

For more scripts and articles, check bellow link.

http://www.bashscript.blogspot.com/

Last edited by radoulov; 10-09-2011 at 07:48 AM.. Reason: Code tags!
 

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Tree::Simple::Visitor::VariableDepthClone(3pm)		User Contributed Perl Documentation	    Tree::Simple::Visitor::VariableDepthClone(3pm)

NAME
Tree::Simple::Visitor::VariableDepthClone - A Visitor for cloning parts of Tree::Simple hierarchy SYNOPSIS
use Tree::Simple::Visitor::VariableDepthClone; # create an visitor my $visitor = Tree::Simple::Visitor::VariableDepthClone->new(); $visitor->setCloneDepth(3); # pass our visitor to the tree $tree->accept($visitor); my $partial_tree = $visitor->getClone(); DESCRIPTION
This visitor will clone METHODS
new There are no arguments to the constructor the object will be in its default state. You can use the "setNodeFilter" method to customize its behavior. includeTrunk ($boolean) Based upon the value of $boolean, this will tell the visitor to include the trunk of the tree in the traversal as well. This basically means it will clone the root node as well. setCloneDepth ($number) setNodeFilter ($filter_function) This method accepts a CODE reference as its $filter_function argument and throws an exception if it is not a code reference. This code reference is used to filter the tree nodes as they are cloned. visit ($tree) This is the method that is used by Tree::Simple's "accept" method. It can also be used on its own, it requires the $tree argument to be a Tree::Simple object (or derived from a Tree::Simple object), and will throw and exception otherwise. getClone This method returns the cloned partial tree. BUGS
None that I am aware of. Of course, if you find a bug, let me know, and I will be sure to fix it. CODE COVERAGE
See the CODE COVERAGE section in Tree::Simple::VisitorFactory for more inforamtion. SEE ALSO
These Visitor classes are all subclasses of Tree::Simple::Visitor, which can be found in the Tree::Simple module, you should refer to that module for more information. AUTHOR
stevan little, <stevan@iinteractive.com> COPYRIGHT AND LICENSE
Copyright 2005 by Infinity Interactive, Inc. <http://www.iinteractive.com> This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. perl v5.10.1 2005-10-24 Tree::Simple::Visitor::VariableDepthClone(3pm)
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