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Full Discussion: Indirect variables in Bash
Top Forums Shell Programming and Scripting Indirect variables in Bash Post 302769088 by DFr0st on Monday 11th of February 2013 06:50:46 AM
Old 02-11-2013
Indirect variables in Bash

Hello,
I've spent hours this morning reading various past forum posts and documentation pages but I can't find exactly what I need.

I'm trying to call a variable with a variable in the name without having to make a third variable.

For example:

Code:
path=AB
legAB=50

leg$path

I want to be able to call leg$path variable and get the value "50"


I am aware that if I created another variable I could do this using the ${! } notation:

Code:
var=leg$path
echo ${!var}=50

However, I want to be able to miss out this last step. Is this possible?
Thanks,
Dan

Last edited by DFr0st; 02-11-2013 at 08:05 AM..
 

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

NAME
Tree::Simple::Visitor::CreateDirectoryTree - A Visitor for create a set of directories and files from a Tree::Simple object SYNOPSIS
use Tree::Simple::Visitor::CreateDirectoryTree; # create a Tree::Simple object which # represents a directory heirarchy my $tree = Tree::Simple->new("www/") ->addChildren( Tree::Simple->new("conf/") ->addChildren( Tree::Simple->new("startup.pl"), Tree::Simple->new("httpd.conf") ), Tree::Simple->new("cgi-bin/"), Tree::Simple->new("ht_docs/"), Tree::Simple->new("logs/") ->addChildren( Tree::Simple->new("error.log"), Tree::Simple->new("access.log") ), ); # create an instance of our visitor my $visitor = Tree::Simple::Visitor::CreateDirectoryTree->new(); # pass the visitor to a Tree::Simple object $tree->accept($visitor); # the www/ directory now mirrors the structure of the tree DESCRIPTION
This visitor can be used to create a set of directories and files from a Tree::Simple object hierarchy. METHODS
new There are no arguments to the constructor the object will be in its default state. You can use the "setNodeFilter", "setFileHandler" and "setDirectoryHandler" methods to customize its behavior. setNodeFilter ($filter_function) This method accepts a CODE reference as its $filter_function argument and throws an exception if it is not a code reference. This code reference is used to filter the tree nodes as they are used to create the directory tree, it can be basically used as a node pre- processor. An example usage of this might be to enforce the 8.3 naming rules of DOS, or the 32 character limit of older macintoshes. setFileHandler ($file_handler) This method accepts a CODE reference as its $file_handler argument and throws an exception if it is not a CODE reference. This method can be used to create custom file creation behavior. The default behavior is to just create the file and nothing else, but by using this method it is possible to implement some other custom behavior, such as creating a file based on a template. The function is passed the full path of the file to be created (as built by File::Spec). setDirectoryHandler ($dir_handler) This method accepts a CODE reference as its $dir_handler argument and throws an exception if it is not a CODE reference. This method can be used to create custom directory creation behavior. The default behavior is to just create the directory and nothing else, but by using this method it is possible to implement some other custom behavior, such as creating a directory on a remote server. The function is passed the full path of the directory to be created (as built by File::Spec). visit ($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. The tree is processed as follows: Any node which is not a leaf is considered a directory. Obviously since files themselves are leaf nodes, this makes sense that non-leaves will be directories. Any node (including leaf nodes) which ends in either the character "/" or "" is considered a directory. I think it is a pretty standard convention to have directory names ending in a separator. The separator itself is stripped off before the directory name is passed to File::Spec where the platform specific directory path is created. This means that it does not matter which one you use, it will be completely cross platform (at least as cross-platform as File::Spec is). All other nodes are considered to be files. 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 2004, 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 2010-02-18 Tree::Simple::Visitor::CreateDirectoryTree(3pm)
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