{"id":349,"date":"2022-07-24T00:00:00","date_gmt":"2022-07-24T00:00:00","guid":{"rendered":"https:\/\/tac.debuzzify.com\/?p=349"},"modified":"2023-06-20T06:25:26","modified_gmt":"2023-06-20T06:25:26","slug":"create-command-line-tools-in-python","status":"publish","type":"post","link":"https:\/\/www.the-analytics.club\/create-command-line-tools-in-python\/","title":{"rendered":"How to Easily Build Command Line Tools in Python?"},"content":{"rendered":"\n<p>It&#8217;s so much easy to develop a command line tool than a <a href=\"https:\/\/towardsdatascience.com\/5-python-gui-frameworks-to-create-desktop-web-and-even-mobile-apps-c25f1bcfb561\" target=\"_blank\" rel=\"noopener\">graphical UI<\/a>. But it&#8217;s easier in Python now than it was before.<\/p>\n\n\n\n\n\n<p><a href=\"\/python-cli-tutorial\">Typer<\/a> is a handy tool that helps convert our ordinary functions into command-line utilities.<\/p>\n\n\n\n<p>A common need in most CLIs is to accept arguments from the user. Typer makes it super easy to do this. Further, Typer also has the flexibility to style your output.<\/p>\n\n\n\n<p>All this happens in two magical lines of code!<\/p>\n\n\n\n<p>Here&#8217;s a simple Python function that accepts a name and says hello. Two lines of Typer code have changed to a CLI.<\/p>\n\n\n\n<p>If you&#8217;re not using Typer, you can <a href=\"\/argparser-example-python-script\">use the standard module, argparser to create CLIs<\/a>. But Typer is so much easier.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Create your first command line tool in Python.<\/h2>\n\n\n\n<p>Before you begin with the rest of the guide, please <a href=\"https:\/\/pypi.org\/project\/typer\/\" target=\"_blank\" rel=\"noopener\">install typer<\/a> on your local computer or your virtual environment. The following code will help.<\/p>\n\n\n\n<p><script><br \/>\n            \/* This is ugly, but to ensure we only create this function once, and only call<br \/>\n            each JS library once, we need to check here in case there are multiple Wagtail<br \/>\n            blocks on this page. This will ensure we only load the minimum payload. *\/<br \/>\n            if(typeof loadPrismLanguage != 'function') {<br \/>\n                window.loadPrismLanguage = function(language) {<br \/>\n                    var libraries = [<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs\",<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/prism.min.js\"<br \/>\n                        },<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs-\" + language,<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/components\/prism-\" + language + \".min.js\"<br \/>\n                        },<br \/>\n        {<br \/>\n            \"id\": \"code-block-line-numbers\",<br \/>\n            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/plugins\/line-numbers\/prism-line-numbers.min.js\"<br \/>\n        }<\/p>\n<p>                    ];<\/p>\n<p>                    for(const library of libraries) {<br \/>\n                        if(document.getElementById(library[\"id\"]) == null) {<br \/>\n                            var s = document.createElement(\"script\");<br \/>\n                            s.id = library[\"id\"];<br \/>\n                            s.type = \"text\/javascript\";<br \/>\n                            s.src = library[\"url\"];<br \/>\n                            s.async = false;<br \/>\n                            document.body.appendChild(s);<br \/>\n                        }<br \/>\n                    }<br \/>\n                };<br \/>\n            }<\/p>\n<p>            loadPrismLanguage('bash');<\/p>\n<p>            language_class_name = 'language-bash';<br \/>\n            <\/script><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>pip install typer&#91;all]<\/code><\/pre>\n\n\n\n<p><script><br \/>\n                var block_num = (typeof block_num === 'undefined') ? 0 : block_num;<br \/>\n                block_num++;<br \/>\n                document.getElementById('target-element-current').className = language_class_name;<br \/>\n                document.getElementById('target-element-current').id = 'target-element-' + block_num;<br \/>\n            <\/script><\/p>\n\n\n\n<p><script><br \/>\n            \/* This is ugly, but to ensure we only create this function once, and only call<br \/>\n            each JS library once, we need to check here in case there are multiple Wagtail<br \/>\n            blocks on this page. This will ensure we only load the minimum payload. *\/<br \/>\n            if(typeof loadPrismLanguage != 'function') {<br \/>\n                window.loadPrismLanguage = function(language) {<br \/>\n                    var libraries = [<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs\",<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/prism.min.js\"<br \/>\n                        },<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs-\" + language,<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/components\/prism-\" + language + \".min.js\"<br \/>\n                        },<br \/>\n        {<br \/>\n            \"id\": \"code-block-line-numbers\",<br \/>\n            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/plugins\/line-numbers\/prism-line-numbers.min.js\"<br \/>\n        }<\/p>\n<p>                    ];<\/p>\n<p>                    for(const library of libraries) {<br \/>\n                        if(document.getElementById(library[\"id\"]) == null) {<br \/>\n                            var s = document.createElement(\"script\");<br \/>\n                            s.id = library[\"id\"];<br \/>\n                            s.type = \"text\/javascript\";<br \/>\n                            s.src = library[\"url\"];<br \/>\n                            s.async = false;<br \/>\n                            document.body.appendChild(s);<br \/>\n                        }<br \/>\n                    }<br \/>\n                };<br \/>\n            }<\/p>\n<p>            loadPrismLanguage('python');<\/p>\n<p>            language_class_name = 'language-python';<br \/>\n            <\/script><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>import typer\n\ndef main(name: str):\n   print(f\"Hello {name}\")\n\nif __name__ == \"__main__\":\n   typer.run(main)<\/code><\/pre>\n\n\n\n<p><script><br \/>\n                var block_num = (typeof block_num === 'undefined') ? 0 : block_num;<br \/>\n                block_num++;<br \/>\n                document.getElementById('target-element-current').className = language_class_name;<br \/>\n                document.getElementById('target-element-current').id = 'target-element-' + block_num;<br \/>\n            <\/script><\/p>\n\n\n\n<p>Say you&#8217;ve named your Python script app.py. If you run the python script on your terminal with an argument, you&#8217;d see it printing hello to your input value.<\/p>\n\n\n\n<p><script><br \/>\n            \/* This is ugly, but to ensure we only create this function once, and only call<br \/>\n            each JS library once, we need to check here in case there are multiple Wagtail<br \/>\n            blocks on this page. This will ensure we only load the minimum payload. *\/<br \/>\n            if(typeof loadPrismLanguage != 'function') {<br \/>\n                window.loadPrismLanguage = function(language) {<br \/>\n                    var libraries = [<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs\",<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/prism.min.js\"<br \/>\n                        },<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs-\" + language,<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/components\/prism-\" + language + \".min.js\"<br \/>\n                        },<br \/>\n        {<br \/>\n            \"id\": \"code-block-line-numbers\",<br \/>\n            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/plugins\/line-numbers\/prism-line-numbers.min.js\"<br \/>\n        }<\/p>\n<p>                    ];<\/p>\n<p>                    for(const library of libraries) {<br \/>\n                        if(document.getElementById(library[\"id\"]) == null) {<br \/>\n                            var s = document.createElement(\"script\");<br \/>\n                            s.id = library[\"id\"];<br \/>\n                            s.type = \"text\/javascript\";<br \/>\n                            s.src = library[\"url\"];<br \/>\n                            s.async = false;<br \/>\n                            document.body.appendChild(s);<br \/>\n                        }<br \/>\n                    }<br \/>\n                };<br \/>\n            }<\/p>\n<p>            loadPrismLanguage('bash');<\/p>\n<p>            language_class_name = 'language-bash';<br \/>\n            <\/script><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>(env) $ python app.py thuwa\nHello thuwa\n\n(env) $ python app.py\nUsage: app.py &#91;OPTIONS] NAME\nTry 'app.py --help' for help.\n\u256d\u2500 Error \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u256e\n\u2502 Missing argument 'NAME'.                                                                                             \u2502\n\u2570\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u256f<\/code><\/pre>\n\n\n\n<p><script><br \/>\n                var block_num = (typeof block_num === 'undefined') ? 0 : block_num;<br \/>\n                block_num++;<br \/>\n                document.getElementById('target-element-current').className = language_class_name;<br \/>\n                document.getElementById('target-element-current').id = 'target-element-' + block_num;<br \/>\n            <\/script><\/p>\n\n\n\n<p>In the above example, you could also see it failing when you try to run the script without an argument. But try adjusting your code and give the name parameter a default value. This makes the command line argument &#8216;name&#8217; an optional one.<\/p>\n\n\n\n<p><script><br \/>\n            \/* This is ugly, but to ensure we only create this function once, and only call<br \/>\n            each JS library once, we need to check here in case there are multiple Wagtail<br \/>\n            blocks on this page. This will ensure we only load the minimum payload. *\/<br \/>\n            if(typeof loadPrismLanguage != 'function') {<br \/>\n                window.loadPrismLanguage = function(language) {<br \/>\n                    var libraries = [<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs\",<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/prism.min.js\"<br \/>\n                        },<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs-\" + language,<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/components\/prism-\" + language + \".min.js\"<br \/>\n                        },<br \/>\n        {<br \/>\n            \"id\": \"code-block-line-numbers\",<br \/>\n            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/plugins\/line-numbers\/prism-line-numbers.min.js\"<br \/>\n        }<\/p>\n<p>                    ];<\/p>\n<p>                    for(const library of libraries) {<br \/>\n                        if(document.getElementById(library[\"id\"]) == null) {<br \/>\n                            var s = document.createElement(\"script\");<br \/>\n                            s.id = library[\"id\"];<br \/>\n                            s.type = \"text\/javascript\";<br \/>\n                            s.src = library[\"url\"];<br \/>\n                            s.async = false;<br \/>\n                            document.body.appendChild(s);<br \/>\n                        }<br \/>\n                    }<br \/>\n                };<br \/>\n            }<\/p>\n<p>            loadPrismLanguage('python');<\/p>\n<p>            language_class_name = 'language-python';<br \/>\n            <\/script><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>def main(name: str = \"world\"):\n    print(f\"Hello {name}\")<\/code><\/pre>\n\n\n\n<p><script><br \/>\n                var block_num = (typeof block_num === 'undefined') ? 0 : block_num;<br \/>\n                block_num++;<br \/>\n                document.getElementById('target-element-current').className = language_class_name;<br \/>\n                document.getElementById('target-element-current').id = 'target-element-' + block_num;<br \/>\n            <\/script><\/p>\n\n\n\n<p><script><br \/>\n            \/* This is ugly, but to ensure we only create this function once, and only call<br \/>\n            each JS library once, we need to check here in case there are multiple Wagtail<br \/>\n            blocks on this page. This will ensure we only load the minimum payload. *\/<br \/>\n            if(typeof loadPrismLanguage != 'function') {<br \/>\n                window.loadPrismLanguage = function(language) {<br \/>\n                    var libraries = [<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs\",<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/prism.min.js\"<br \/>\n                        },<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs-\" + language,<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/components\/prism-\" + language + \".min.js\"<br \/>\n                        },<br \/>\n        {<br \/>\n            \"id\": \"code-block-line-numbers\",<br \/>\n            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/plugins\/line-numbers\/prism-line-numbers.min.js\"<br \/>\n        }<\/p>\n<p>                    ];<\/p>\n<p>                    for(const library of libraries) {<br \/>\n                        if(document.getElementById(library[\"id\"]) == null) {<br \/>\n                            var s = document.createElement(\"script\");<br \/>\n                            s.id = library[\"id\"];<br \/>\n                            s.type = \"text\/javascript\";<br \/>\n                            s.src = library[\"url\"];<br \/>\n                            s.async = false;<br \/>\n                            document.body.appendChild(s);<br \/>\n                        }<br \/>\n                    }<br \/>\n                };<br \/>\n            }<\/p>\n<p>            loadPrismLanguage('bash');<\/p>\n<p>            language_class_name = 'language-bash';<br \/>\n            <\/script><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>(env) $ python app.py\nHello world<\/code><\/pre>\n\n\n\n<p><script><br \/>\n                var block_num = (typeof block_num === 'undefined') ? 0 : block_num;<br \/>\n                block_num++;<br \/>\n                document.getElementById('target-element-current').className = language_class_name;<br \/>\n                document.getElementById('target-element-current').id = 'target-element-' + block_num;<br \/>\n            <\/script><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Create multiple command line functions in the same Python script.<\/h2>\n\n\n\n<p>Often you&#8217;d want to have more than one function on your Python script. In such cases, you can choose which parts appear as command line utilities.<\/p>\n\n\n\n<p>For instance, the following script has three Python functions. One is to say hi, and the other is to say bye. We also have a third function to tell &#8216;Run Away.&#8217;<\/p>\n\n\n\n<p>We want to convert the first two into command line functions and leave the last one.<\/p>\n\n\n\n<p>The following script does it.<\/p>\n\n\n\n<p><script><br \/>\n            \/* This is ugly, but to ensure we only create this function once, and only call<br \/>\n            each JS library once, we need to check here in case there are multiple Wagtail<br \/>\n            blocks on this page. This will ensure we only load the minimum payload. *\/<br \/>\n            if(typeof loadPrismLanguage != 'function') {<br \/>\n                window.loadPrismLanguage = function(language) {<br \/>\n                    var libraries = [<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs\",<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/prism.min.js\"<br \/>\n                        },<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs-\" + language,<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/components\/prism-\" + language + \".min.js\"<br \/>\n                        },<br \/>\n        {<br \/>\n            \"id\": \"code-block-line-numbers\",<br \/>\n            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/plugins\/line-numbers\/prism-line-numbers.min.js\"<br \/>\n        }<\/p>\n<p>                    ];<\/p>\n<p>                    for(const library of libraries) {<br \/>\n                        if(document.getElementById(library[\"id\"]) == null) {<br \/>\n                            var s = document.createElement(\"script\");<br \/>\n                            s.id = library[\"id\"];<br \/>\n                            s.type = \"text\/javascript\";<br \/>\n                            s.src = library[\"url\"];<br \/>\n                            s.async = false;<br \/>\n                            document.body.appendChild(s);<br \/>\n                        }<br \/>\n                    }<br \/>\n                };<br \/>\n            }<\/p>\n<p>            loadPrismLanguage('python');<\/p>\n<p>            language_class_name = 'language-python';<br \/>\n            <\/script><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>import typer\n\napp = typer.Typer()\n\n\n@app.command()\ndef say_hi(name: str):\n    print(f\"Hello {name}\")\n\n\n@app.command()\ndef say_bye(name: str):\n    print(f\"Bye {name}!\")\n\n\nif __name__ == \"__main__\":\n    app()<\/code><\/pre>\n\n\n\n<p><script><br \/>\n                var block_num = (typeof block_num === 'undefined') ? 0 : block_num;<br \/>\n                block_num++;<br \/>\n                document.getElementById('target-element-current').className = language_class_name;<br \/>\n                document.getElementById('target-element-current').id = 'target-element-' + block_num;<br \/>\n            <\/script><\/p>\n\n\n\n<p>This script may look a bit more complicated than the previous simple example. But it is not.<\/p>\n\n\n\n<p>In this example, we create a Typer app and manually add commands to it. We add commands by annotating functions with `@app.command`.<\/p>\n\n\n\n<p>In the main app, we called our app itself.<\/p>\n\n\n\n<p>Now run the script with <code>--help<\/code> at the end and see the beautiful help document printing on the screen.<\/p>\n\n\n\n<p><script><br \/>\n            \/* This is ugly, but to ensure we only create this function once, and only call<br \/>\n            each JS library once, we need to check here in case there are multiple Wagtail<br \/>\n            blocks on this page. This will ensure we only load the minimum payload. *\/<br \/>\n            if(typeof loadPrismLanguage != 'function') {<br \/>\n                window.loadPrismLanguage = function(language) {<br \/>\n                    var libraries = [<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs\",<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/prism.min.js\"<br \/>\n                        },<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs-\" + language,<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/components\/prism-\" + language + \".min.js\"<br \/>\n                        },<br \/>\n        {<br \/>\n            \"id\": \"code-block-line-numbers\",<br \/>\n            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/plugins\/line-numbers\/prism-line-numbers.min.js\"<br \/>\n        }<\/p>\n<p>                    ];<\/p>\n<p>                    for(const library of libraries) {<br \/>\n                        if(document.getElementById(library[\"id\"]) == null) {<br \/>\n                            var s = document.createElement(\"script\");<br \/>\n                            s.id = library[\"id\"];<br \/>\n                            s.type = \"text\/javascript\";<br \/>\n                            s.src = library[\"url\"];<br \/>\n                            s.async = false;<br \/>\n                            document.body.appendChild(s);<br \/>\n                        }<br \/>\n                    }<br \/>\n                };<br \/>\n            }<\/p>\n<p>            loadPrismLanguage('bash');<\/p>\n<p>            language_class_name = 'language-bash';<br \/>\n            <\/script><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>(env) $ python app.py --help\n                                                                                                                        \n Usage: app.py &#91;OPTIONS] COMMAND &#91;ARGS]...                                                                              \n                                                                                                                        \n\u256d\u2500 Options \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u256e\n\u2502 --install-completion          Install completion for the current shell.                                              \u2502\n\u2502 --show-completion             Show completion for the current shell, to copy it or customize the installation.       \u2502\n\u2502 --help                        Show this message and exit.                                                            \u2502\n\u2570\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u256f\n\u256d\u2500 Commands \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u256e\n\u2502 say-bye                                                                                                              \u2502\n\u2502 say-hi                                                                                                               \u2502\n\u2570\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u256f<\/code><\/pre>\n\n\n\n<p><script><br \/>\n                var block_num = (typeof block_num === 'undefined') ? 0 : block_num;<br \/>\n                block_num++;<br \/>\n                document.getElementById('target-element-current').className = language_class_name;<br \/>\n                document.getElementById('target-element-current').id = 'target-element-' + block_num;<br \/>\n            <\/script><\/p>\n\n\n\n<p>In the help menu, you can see the two functions we&#8217;ve annotated with `@app.command`. We can use these with arguments in our command line.<\/p>\n\n\n\n<p>We can also see that the runaway function is not a CLI, although it&#8217;s there in the script. If we try to run this command, it&#8217;ll fail as shown below.<\/p>\n\n\n\n<p><script><br \/>\n            \/* This is ugly, but to ensure we only create this function once, and only call<br \/>\n            each JS library once, we need to check here in case there are multiple Wagtail<br \/>\n            blocks on this page. This will ensure we only load the minimum payload. *\/<br \/>\n            if(typeof loadPrismLanguage != 'function') {<br \/>\n                window.loadPrismLanguage = function(language) {<br \/>\n                    var libraries = [<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs\",<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/prism.min.js\"<br \/>\n                        },<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs-\" + language,<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/components\/prism-\" + language + \".min.js\"<br \/>\n                        },<br \/>\n        {<br \/>\n            \"id\": \"code-block-line-numbers\",<br \/>\n            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/plugins\/line-numbers\/prism-line-numbers.min.js\"<br \/>\n        }<\/p>\n<p>                    ];<\/p>\n<p>                    for(const library of libraries) {<br \/>\n                        if(document.getElementById(library[\"id\"]) == null) {<br \/>\n                            var s = document.createElement(\"script\");<br \/>\n                            s.id = library[\"id\"];<br \/>\n                            s.type = \"text\/javascript\";<br \/>\n                            s.src = library[\"url\"];<br \/>\n                            s.async = false;<br \/>\n                            document.body.appendChild(s);<br \/>\n                        }<br \/>\n                    }<br \/>\n                };<br \/>\n            }<\/p>\n<p>            loadPrismLanguage('bash');<\/p>\n<p>            language_class_name = 'language-bash';<br \/>\n            <\/script><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>env) $ python app.py say-hi thuwa\nHello thuwa\n(env) $ python app.py say-bye thuwa\nBye thuwa!\n(env) $ python app.py run-away thuwa\nUsage: app.py &#91;OPTIONS] COMMAND &#91;ARGS]...\nTry 'app.py --help' for help.\n\u256d\u2500 Error \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u256e\n\u2502 No such command 'run-away'.                                                                                          \u2502\n\u2570\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u256f<\/code><\/pre>\n\n\n\n<p><script><br \/>\n                var block_num = (typeof block_num === 'undefined') ? 0 : block_num;<br \/>\n                block_num++;<br \/>\n                document.getElementById('target-element-current').className = language_class_name;<br \/>\n                document.getElementById('target-element-current').id = 'target-element-' + block_num;<br \/>\n            <\/script><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Running shell commands in your CLI.<\/h2>\n\n\n\n<p>I&#8217;ve wanted to write a find and replace command. It should go inside every file in the current directory and replace values.<\/p>\n\n\n\n<p>You can do it in Linux using the following command.<\/p>\n\n\n\n<p><code>find .\/ -type f -exec sed -i -e 's\/&lt;FIND VALUE&gt;\/&lt;REPLACE VALUE&gt;\/g' {} \\;<\/code><\/p>\n\n\n\n<p>Yet, the above function is hard to memorize and reuse. Let&#8217;s create a convenient Python wrapper around it.<\/p>\n\n\n\n<p>We can run this <a href=\"\/python-shell-commands\">shell command inside Python<\/a>.<\/p>\n\n\n\n<p><script><br \/>\n            \/* This is ugly, but to ensure we only create this function once, and only call<br \/>\n            each JS library once, we need to check here in case there are multiple Wagtail<br \/>\n            blocks on this page. This will ensure we only load the minimum payload. *\/<br \/>\n            if(typeof loadPrismLanguage != 'function') {<br \/>\n                window.loadPrismLanguage = function(language) {<br \/>\n                    var libraries = [<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs\",<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/prism.min.js\"<br \/>\n                        },<br \/>\n                        {<br \/>\n                            \"id\": \"code-block-prismjs-\" + language,<br \/>\n                            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/components\/prism-\" + language + \".min.js\"<br \/>\n                        },<br \/>\n        {<br \/>\n            \"id\": \"code-block-line-numbers\",<br \/>\n            \"url\": \"\/\/cdnjs.cloudflare.com\/ajax\/libs\/prism\/1.25.0\/plugins\/line-numbers\/prism-line-numbers.min.js\"<br \/>\n        }<\/p>\n<p>                    ];<\/p>\n<p>                    for(const library of libraries) {<br \/>\n                        if(document.getElementById(library[\"id\"]) == null) {<br \/>\n                            var s = document.createElement(\"script\");<br \/>\n                            s.id = library[\"id\"];<br \/>\n                            s.type = \"text\/javascript\";<br \/>\n                            s.src = library[\"url\"];<br \/>\n                            s.async = false;<br \/>\n                            document.body.appendChild(s);<br \/>\n                        }<br \/>\n                    }<br \/>\n                };<br \/>\n            }<\/p>\n<p>            loadPrismLanguage('python');<\/p>\n<p>            language_class_name = 'language-python';<br \/>\n            <\/script><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>import typer\nimport subprocess\n\n\ndef replace(old: str, new: str):\n    \"\"\"Find and replace 'old' with 'new' in every file in the current directory\"\"\"\n\n    command = &#91;\n        \"find\",\n        \".\/\",\n        \"-type\",\n        \"f\",\n        \"-exec\",\n        \"sed\",\n        \"-i\",\n        f\"s\/{old}\/{new}\/g\",\n        \"{}\",\n        \";\",\n    ]\n\n    subprocess.call(command)\n\n\nif __name__ == \"__main__\":\n    typer.run(replace)<\/code><\/pre>\n\n\n\n<p><script><br \/>\n                var block_num = (typeof block_num === 'undefined') ? 0 : block_num;<br \/>\n                block_num++;<br \/>\n                document.getElementById('target-element-current').className = language_class_name;<br \/>\n                document.getElementById('target-element-current').id = 'target-element-' + block_num;<br \/>\n            <\/script><\/p>\n\n\n\n<p>This may not be a very Pythonic way to find and replace values in a folder. But it explains well how to run shell commands inside your CLI wrapper.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>You can build CLIs with Typer. It can accept command line arguments and get the output printed on the terminal.<\/p>\n","protected":false},"author":2,"featured_media":626,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_kad_blocks_custom_css":"","_kad_blocks_head_custom_js":"","_kad_blocks_body_custom_js":"","_kad_blocks_footer_custom_js":"","_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"footnotes":""},"categories":[3,5],"tags":[],"taxonomy_info":{"category":[{"value":3,"label":"Python"},{"value":5,"label":"Programming"}]},"featured_image_src_large":["https:\/\/www.the-analytics.club\/wp-content\/uploads\/2023\/06\/5935794-1024x683.jpg",1024,683,true],"author_info":{"display_name":"Thuwarakesh","author_link":"https:\/\/www.the-analytics.club\/author\/thuwarakesh\/"},"comment_info":0,"category_info":[{"term_id":3,"name":"Python","slug":"python","term_group":0,"term_taxonomy_id":3,"taxonomy":"category","description":"","parent":5,"count":52,"filter":"raw","cat_ID":3,"category_count":52,"category_description":"","cat_name":"Python","category_nicename":"python","category_parent":5},{"term_id":5,"name":"Programming","slug":"programming","term_group":0,"term_taxonomy_id":5,"taxonomy":"category","description":"","parent":0,"count":43,"filter":"raw","cat_ID":5,"category_count":43,"category_description":"","cat_name":"Programming","category_nicename":"programming","category_parent":0}],"tag_info":false,"_links":{"self":[{"href":"https:\/\/www.the-analytics.club\/wp-json\/wp\/v2\/posts\/349"}],"collection":[{"href":"https:\/\/www.the-analytics.club\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.the-analytics.club\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.the-analytics.club\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.the-analytics.club\/wp-json\/wp\/v2\/comments?post=349"}],"version-history":[{"count":2,"href":"https:\/\/www.the-analytics.club\/wp-json\/wp\/v2\/posts\/349\/revisions"}],"predecessor-version":[{"id":628,"href":"https:\/\/www.the-analytics.club\/wp-json\/wp\/v2\/posts\/349\/revisions\/628"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.the-analytics.club\/wp-json\/wp\/v2\/media\/626"}],"wp:attachment":[{"href":"https:\/\/www.the-analytics.club\/wp-json\/wp\/v2\/media?parent=349"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.the-analytics.club\/wp-json\/wp\/v2\/categories?post=349"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.the-analytics.club\/wp-json\/wp\/v2\/tags?post=349"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}