{"id":605,"date":"2022-05-06T09:48:00","date_gmt":"2022-05-06T09:48:00","guid":{"rendered":"https:\/\/andrejacobs.org\/?p=605"},"modified":"2022-05-27T15:56:55","modified_gmt":"2022-05-27T15:56:55","slug":"learning-go-day-11","status":"publish","type":"post","link":"https:\/\/andrejacobs.org\/study-notes\/learning-go-day-11\/","title":{"rendered":"Learning Go &#8211; Day 11"},"content":{"rendered":"\n<p class=\"has-small-font-size\">Featured image by&nbsp;<a href=\"https:\/\/github.com\/egonelbre\/gophers\" target=\"_blank\" rel=\"noreferrer noopener\">Egon Elbre<\/a><\/p>\n\n\n\n<div class=\"wp-block-jetpack-markdown\"><h3>Adding GOPATH to $PATH<\/h3>\n<ul>\n<li>I added <code>$(go env GOPATH)\/bin<\/code> to my $PATH environment variable. For me this involved modifying my custom zsh resources.<\/li>\n<\/ul>\n<h3>Handling OS signals<\/h3>\n<p>You can use the <code>os\/signal<\/code> package to listen for signal notifications sent to your process.<\/p>\n<ul>\n<li>Create a channel to receive notifications on: <code>make(chan os.Signal, 1)<\/code><\/li>\n<li>Register to receive notifications for signals: <code>signal.Notify()<\/code><\/li>\n<li>Stop receiving notifications: <code>signal.Stop()<\/code><\/li>\n<\/ul>\n<p>The following example will run in an infinite loop until you either press <code>Ctrl+C<\/code> or kill the process.<\/p>\n<pre><code class=\"language-go\">package main\n\nimport (\n\t&quot;fmt&quot;\n\t&quot;os&quot;\n\t&quot;os\/signal&quot;\n\t&quot;syscall&quot;\n)\n\nfunc main() {\n\tfmt.Printf(&quot;Running forever until you either press Ctrl+C or `kill %d`\\n&quot;, syscall.Getpid())\n\n\tsigCh := make(chan os.Signal, 1)\n\n\tsignal.Notify(sigCh, syscall.SIGINT, syscall.SIGABRT)\n\n\tfor {\n\t\tselect {\n\t\tcase recvSig := &lt;-sigCh:\n\t\t\tsignal.Stop(sigCh)\n\t\t\tfmt.Printf(&quot;\\nReceived signal: %s\\n&quot;, recvSig)\n\t\t\treturn\n\t\t}\n\t}\n}\n<\/code><\/pre>\n<pre><code class=\"language-bash\"># User pressed Ctrl+C example\n$ go run .\nRunning forever until you either press Ctrl+C or `kill 35417`\n^C\nReceived signal: interrupt\n<\/code><\/pre>\n<pre><code class=\"language-bash\"># Process was killed\nterminal1$ go run .\nRunning forever until you either press Ctrl+C or `kill 35454`\n\nterminal2$ kill 35454\n\nterminal1$\n...\nsignal: terminated\n<\/code><\/pre>\n<h3>Cobra<\/h3>\n<p><a href=\"https:\/\/github.com\/spf13\/cobra\">Cobra<\/a> has become sort of a staple for writing CLIs in the golang world and it is awesome!<\/p>\n<ul>\n<li>Adding Cobra as a dependency.<\/li>\n<\/ul>\n<pre><code class=\"language-bash\">$ go get -u github.com\/spf13\/cobra@latest\n<\/code><\/pre>\n<ul>\n<li>Installing Cobra so we can use the code generation tool.<\/li>\n<\/ul>\n<pre><code class=\"language-bash\">$ go install github.com\/spf13\/cobra-cli@latest\n<\/code><\/pre>\n<ul>\n<li>Configure the default author and license to use when generating code. Create a file <code>~\/.cobra.yaml<\/code><\/li>\n<\/ul>\n<pre><code class=\"language-yaml\">author: Andre Jacobs\nlicense: MIT\n<\/code><\/pre>\n<ul>\n<li>Starting a new Cobra based project.<\/li>\n<\/ul>\n<pre><code class=\"language-bash\">$ mkdir projectSomething\n$ cd projectSomething\n$ go mod init projectSomething   #NOTE: not the best naming if you are going to share this\n\n$ go get -u github.com\/spf13\/cobra@latest\n\n$ cobra-cli init\n\n$ tree\n.\n\u251c\u2500\u2500 LICENSE\n\u251c\u2500\u2500 cmd\n\u2502\u00a0\u00a0 \u2514\u2500\u2500 root.go\n\u251c\u2500\u2500 go.mod\n\u251c\u2500\u2500 go.sum\n\u2514\u2500\u2500 main.go\n\n1 directory, 5 files\n<\/code><\/pre>\n<ul>\n<li>Note how it creates the LICENSE files and the root command underneath cmd directory.<\/li>\n<li>Adding a new subcommand.<\/li>\n<\/ul>\n<pre><code class=\"language-bash\">$ cobra-cli add buylego\n...\n$ tree\n.\n\u251c\u2500\u2500 LICENSE\n\u251c\u2500\u2500 cmd\n\u2502\u00a0\u00a0 \u2514\u2500\u2500 buylego.go\n\u2502\u00a0\u00a0 \u2514\u2500\u2500 root.go\n\u251c\u2500\u2500 go.mod\n\u251c\u2500\u2500 go.sum\n\u2514\u2500\u2500 main.go\n<\/code><\/pre>\n<ul>\n<li>Adding a new subcommand to another parent command (e.g. not to root). NOTE: -p specifies the instance variable name of the command and not the command name it self.<\/li>\n<\/ul>\n<pre><code class=\"language-bash\">$ cobra-cli add list -p buylegoCmd\n<\/code><\/pre>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Featured image by&nbsp;Egon Elbre [&#8230;]<\/p>\n<p><a class=\"understrap-read-more-link\" href=\"https:\/\/andrejacobs.org\/study-notes\/learning-go-day-11\/\">Read more &rarr;<\/a><\/p>\n","protected":false},"author":2,"featured_media":580,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_mi_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[52],"tags":[53],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v19.13 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Learning Go - Day 11 - Andr\u00e9 Jacobs<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/andrejacobs.org\/study-notes\/learning-go-day-11\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Learning Go - Day 11 - Andr\u00e9 Jacobs\" \/>\n<meta property=\"og:description\" content=\"Featured image by&nbsp;Egon Elbre [...]Read more &rarr;\" \/>\n<meta property=\"og:url\" content=\"https:\/\/andrejacobs.org\/study-notes\/learning-go-day-11\/\" \/>\n<meta property=\"og:site_name\" content=\"Andr\u00e9 Jacobs\" \/>\n<meta property=\"article:published_time\" content=\"2022-05-06T09:48:00+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2022-05-27T15:56:55+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/andrejacobs.org\/wp-content\/uploads\/2022\/05\/ballet.png\" \/>\n\t<meta property=\"og:image:width\" content=\"399\" \/>\n\t<meta property=\"og:image:height\" content=\"486\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/png\" \/>\n<meta name=\"author\" content=\"Andr\u00e9 Jacobs\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@andrejacobs81\" \/>\n<meta name=\"twitter:site\" content=\"@andrejacobs81\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Andr\u00e9 Jacobs\" \/>\n\t<meta name=\"twitter:label2\" content=\"Estimated reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/andrejacobs.org\/study-notes\/learning-go-day-11\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/andrejacobs.org\/study-notes\/learning-go-day-11\/\"},\"author\":{\"name\":\"Andr\u00e9 Jacobs\",\"@id\":\"https:\/\/andrejacobs.org\/#\/schema\/person\/3d38360883015e883c80c2fb875c5a68\"},\"headline\":\"Learning Go &#8211; 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