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Full Discussion: "let" in BASH
Top Forums Shell Programming and Scripting "let" in BASH Post 302915039 by Perderabo on Saturday 30th of August 2014 11:01:41 PM
Old 08-31-2014
The "let" command originated in ksh. Dave Korn considered it to be a mistake and very quickly developed the double parentheses notation to replace it. By the mid 1980's the advice was to not use the "let" command in new code. However the let command is still available. It is intended for legacy code. bash copied ksh arithmetic including both the double parentheses and the "let" command. And the bash team followed Dave's lead in not recommending the "let" command.

I started using ksh in the late 80's. The "let" command had been deprecated for several years even back then. I have been writing ksh scripts form over a quarter of a century. I don't believe that I have ever used "let". I don't believe that I ever will.
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COROSYNC-OBJCTL(8)					      System Manager's Manual						COROSYNC-OBJCTL(8)

NAME
corosync-objctl - Configure objects in the Object Database SYNOPSIS
corosync-objctl [-b] [-c|-w|-d|-a|-t-h] <OBJECT-SPEC>... DESCRIPTION
corosync-objctl is used to configure objects within the object database at runtime. OBJECT-SPEC There are two types of entities Objects and Key=Value pairs Objects Objects are container like entities that can hold other entities. They are specified as "objectA"."objectB". An example is log- ging.logger. Key=Value pairs These are the entities that actually hold values (read database "fields"). They are specified as object.key=value or just object.key if you are reading. OPTIONS
-c Create a new object. -d Delete an existing object. -w Use this option when you want to write a new value to a key. -a Display all values currently available. -t Track changes to an object and it's children. As changes are made to the object they are printed out. this is kind of like a "tail -f" for the object database. -h Print basic usage. -b Display binary values in BASH backslash escape sequences format. EXAMPLES
Print the objOne object (shouldn't exist yet). $ corosync-objctl objOne Create the objOne object. $ corosync-objctl -c objOne Print the objOne object (empty). $ corosync-objctl objOne objOne Write two new keys to the objOne object. $ corosync-objctl -w objOne.max=3000 objOne.min=100 Print the objOne object (with the two new keys). $ corosync-objctl objOne objOne.min=100 objOne.max=3000 Delete the objOne.min key $ corosync-objctl -d objOne.min=100 Prove that is gone. $ corosync-objctl objOne objOne.max=3000 Delete the whole objOne object. $ corosync-objctl -d objOne Prove that is gone. $ corosync-objctl objOne SEE ALSO
confdb_initialize(3), AUTHOR
Angus Salkeld 2008-07-29 COROSYNC-OBJCTL(8)
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