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Showing posts from October 4, 2009

Windows environment variables basics

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Perm url with updates: http://xahlee.org/mswin/env_var.htmlWindows Environment VariablesXah Lee, 2009-10-03, 2010-06-18This document is a basic tutorial about Windows's Environment Variables. The code here is tested on Windows Vista.Environment variables are system-wide global variables. They are somewhat like config parameters, and is used by processes. For example, apps need to know the path of your Windows kernal, path to cmd.exe, path of your home dir, paths to search for shell programs, etc.To view and set your env var, go to Control Panel, then click the “System” icon, then click the “Advanced system settings” link, then “Advanced” tab, Environment Variables button.The Windows System control panel for editing env vars. You can launch the app directly in cmd.exe or PowerShell by typing the following (Windows Vista): c:/Windows/System32/SystemPropertiesAdvanced.exe Env var names are not case sensitive. So, “PATH”, “Path”, “path” are treated the same.Sample Values Of Env VarHere…

Lambda Logo Tour

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Perm url with updates: http://xahlee.org/UnixResource_dir/lambda_logo.htmlA Lambda Logo Tour(and why LISP languages using λ as logo should not be looked upon kindly)Xah Lee, 2002-02, ..., 2010-09-25Dear lispers,The lambda character λ, always struck a awe in me, as with other mathematical symbols. In my mind, i imagine that those obscure math symbolism are etched in stone by god. A salient example is the book cover Concrete Mathematics by Ronald Graham et al. amazonBook cover of Concrete Mathematics. Here we see the summation sign ∑ etched in stone. The summation sign happens to be my favorite math symbol. (chosen as my website signet: )These symbols are not to be trifled with. If anyone puffs in as much half a snicker, i wish god strikes a thunder upon their impudence.Promote your logo with these custom promotional items for your brand. The Greek lambda symbol is used in a branch of logic called lambda calculus. The theories of lambda calculus is what functional languages are based on…