{"id":2672,"date":"2019-10-06T14:49:04","date_gmt":"2019-10-06T13:49:04","guid":{"rendered":"http:\/\/www.dpscomputing.com\/blog\/?p=2672"},"modified":"2021-03-01T21:35:18","modified_gmt":"2021-03-01T21:35:18","slug":"set-windows-environment-variables-from-command-line","status":"publish","type":"post","link":"https:\/\/www.dpscomputing.com\/blog\/2019\/10\/06\/set-windows-environment-variables-from-command-line\/","title":{"rendered":"Set Windows Environment Variables From Command Line"},"content":{"rendered":"\n
\"\"<\/figure><\/div>\n\n\n\n

OK, sure there is a GUI in Windows for this – in Advanced – Environment Variables<\/a> accessed via the System control panel app. <\/p>\n\n\n\n

But. a) where is the fun in that? And b) if you’re doing some development, switching to various different interfaces, keeping control panel apps open etc is a bit of a bore as well as being incredibly inefficient. <\/p>\n\n\n\n

During development such as Node.js<\/a> development, you’re probably going to want to tinker with the environment variables reasonably regularly. <\/p>\n\n\n\n

What is the top change that a Node developer will want to make during development to these variables? Answer: switching debugging on (and then off) again. <\/p>\n\n\n\n

Ever spun up a server in Node and something’s gone awry? Then you might want to debug the HTTP library requests. <\/p>\n\n\n\n

The examples below are setting environment variables relating to Node.js, but the commands can be used to set up – or indeed create – any environment variables of your choosing. <\/p>\n\n\n\n

The Server Example<\/h2>\n\n\n\n

The famous server example<\/a>, that has pride and place in Node’s own documentation, is what we will be looking at today. Well, at least a variant of it – there are a few after all. <\/p>\n\n\n\n

const http = require('http');\n\nconst server = http.createServer((req, res) => {\n    res.end('Hello World.  This is David!\\n');\n});\n\nserver.listen(4242, () => {\n    console.log('Server is running...');\n});<\/code><\/pre>\n\n\n\n
This is in a simple JavaScript file called ‘hello-world.js’.  <\/p>\n\n\n\n
So, if we run this without debug mode on (default), the output that we get in the console is:<\/p>\n\n\n\n
PS H:\\NodeCode> node hello-world\nServer is running...<\/code><\/pre>\n\n\n\n
Open a browser, head to localhost:4242 and here’s what you should get:<\/p>\n\n\n\n
\"\"<\/figure>\n\n\n\n
So, everything in this case is peachy, but what happens if it’s not?  <\/p>\n\n\n\n
Setting An Environment Variable<\/h2>\n\n\n\n
As previously mentioned, this example is the context of Node.js development – but can apply to any Environment Variable that you want to set for any reason what so ever.  <\/p>\n\n\n\n
We’re wanting to switch on debugging for the HTTP library specifically so, on the command line:<\/p>\n\n\n\n
PS H:\\NodeCode> $env:NODE_DEBUG=\"http\"<\/code><\/pre>\n\n\n\n
Simple as that!  <\/p>\n\n\n\n
Stop the server executing (CTRL + C twice) in the console and restart again using the previously used command.  Visit the web page in your browser – localhost:4242 and take a look at the different output:<\/p>\n\n\n\n
PS H:\\NodeCode> node 1-hello-world\nServer is running...\nHTTP 15920: SERVER new http connection\nHTTP 15920: SERVER new http connection\nHTTP 15920: write ret = true\nHTTP 15920: outgoing message end.\nHTTP 15920: SERVER socketOnParserExecute 828\nHTTP 15920: resetHeadersTimeoutOnReqEnd\nHTTP 15920: write ret = true\nHTTP 15920: outgoing message end.\nHTTP 15920: SERVER socketOnParserExecute 749\nHTTP 15920: resetHeadersTimeoutOnReqEnd<\/code><\/pre>\n\n\n\n
Clearing an Environment Variable<\/h2>\n\n\n\n
Again, our example is in the context of Node.js – but it’s the same for clearing any environment variable.  <\/p>\n\n\n\n
Head back to the command line and:<\/p>\n\n\n\n
PS H:\\NodeCode> $env:NODE_DEBUG=\"\"<\/code><\/pre>\n\n\n\n
We’re back to where we started.  Good job!<\/p>\n\n\n\n
Old School Command Line<\/h2>\n\n\n\n
Are you on an older version of Windows?  Maybe you’re just stuck using the old school command line?  If so, please do start using PowerShell.  <\/p>\n\n\n\n
But, if you do insist, you’ll have to tweak the call setting the environment variable so that it works on this ye olde setup:<\/p>\n\n\n\n
H:\\NodeCode>set NODE_DEBUG=\"http\"<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
OK, sure there is a GUI in Windows for this – in Advanced – Environment Variables accessed via the System control panel app. But. a) where is the fun in that? And b) if...<\/p>\n","protected":false},"author":1,"featured_media":2674,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"You want me to set a what on a who-what?\n\nSet Windows Environment Variables From Command Line\n\nExamples in #NodeJS\n\n#WindowsEnvrionmentVariables #DebuggingNodeJS","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false},"version":2}},"categories":[55],"tags":[2495,2489,2490,2493,2494,2496,2492,2491,2488],"class_list":["post-2672","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-articles","tag-debugging-node-environment-variables","tag-enviornment-variables","tag-environment-vars","tag-how-to-set-windows-environment-variables","tag-node-environment-variables","tag-node-environment-variables-on-windows","tag-setting-windows-enviornment-variables","tag-settings-environment-variables","tag-windows-environment-variables"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/www.dpscomputing.com\/blog\/wp-content\/uploads\/2019\/10\/image-27.png","jetpack_shortlink":"https:\/\/wp.me\/p3nsfA-H6","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"_links":{"self":[{"href":"https:\/\/www.dpscomputing.com\/blog\/wp-json\/wp\/v2\/posts\/2672","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.dpscomputing.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.dpscomputing.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.dpscomputing.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.dpscomputing.com\/blog\/wp-json\/wp\/v2\/comments?post=2672"}],"version-history":[{"count":2,"href":"https:\/\/www.dpscomputing.com\/blog\/wp-json\/wp\/v2\/posts\/2672\/revisions"}],"predecessor-version":[{"id":3030,"href":"https:\/\/www.dpscomputing.com\/blog\/wp-json\/wp\/v2\/posts\/2672\/revisions\/3030"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.dpscomputing.com\/blog\/wp-json\/wp\/v2\/media\/2674"}],"wp:attachment":[{"href":"https:\/\/www.dpscomputing.com\/blog\/wp-json\/wp\/v2\/media?parent=2672"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.dpscomputing.com\/blog\/wp-json\/wp\/v2\/categories?post=2672"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.dpscomputing.com\/blog\/wp-json\/wp\/v2\/tags?post=2672"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}