diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..40b878d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+node_modules/
\ No newline at end of file
diff --git a/.jshintrc b/.jshintrc
new file mode 100644
index 0000000..8ab3485
--- /dev/null
+++ b/.jshintrc
@@ -0,0 +1,3 @@
+{
+    "esversion": 6
+}
\ No newline at end of file
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..57028d9
--- /dev/null
+++ b/README.md
@@ -0,0 +1,9 @@
+## Aplicación de comandos
+
+Este es el ejercicio del curso
+
+Recuerden instalar los paquetes de node
+
+````
+npm install
+````
\ No newline at end of file
diff --git a/app.js b/app.js
new file mode 100644
index 0000000..7092e4f
--- /dev/null
+++ b/app.js
@@ -0,0 +1,35 @@
+// const argv = require('yargs').argv;
+const argv = require('./config/yargs').argv;
+const porHacer = require('./por-hacer/por-hacer');
+var colors = require('colors');
+
+
+
+let comando = argv._[0];
+
+switch (comando) {
+    case 'crear':
+        let tarea = porHacer.crear(argv.descripcion);
+        console.log(tarea);
+        break;
+    case 'listar':
+        let listado = porHacer.getListado();
+
+        for (let tarea of listado) {
+            console.log('=====Por Hacer====='.green);
+            console.log(tarea.descripcion);
+            console.log('Estado: ', tarea.completado);
+            console.log('==================='.green);
+        }
+        break;
+    case 'actualizar':
+        let actualizado = porHacer.actualizar(argv.descripcion, argv.completado);
+        console.log(actualizado);
+        break;
+    case 'borrar':
+        let borrado = porHacer.borrar(argv.descripcion);
+        console.log(borrado);
+        break;
+    default:
+        console.log('Comando no reconocido');
+}
\ No newline at end of file
diff --git a/config/yargs.js b/config/yargs.js
new file mode 100644
index 0000000..9475ce2
--- /dev/null
+++ b/config/yargs.js
@@ -0,0 +1,34 @@
+const opcionesCrear = {
+    descripcion: {
+        demand: true,
+        alias: 'd',
+        desc: 'Descripción de la tarea por hacer'
+    }
+};
+const opcionesActualizar = {
+    descripcion: {
+        demand: true,
+        alias: 'd',
+        desc: 'Descripción de la tarea por actualizar'
+    },
+    completado: {
+        alias: 'c',
+        default: true,
+        desc: 'Marca como completado o pendiente la tarea'
+    }
+};
+const opcionesBorrar = {
+    descripcion: {
+        demand: true,
+        alias: 'd',
+        desc: 'Descripción de la tarea por borrar'
+    }
+};
+const argv = require('yargs')
+    .command('crear', 'Crear un elemento por hacer', opcionesCrear)
+    .command('actualizar', 'Actualiza el estrado completado de una tarea', opcionesActualizar)
+    .command('borrar', 'Borra la tarea pasada como descripcion', opcionesBorrar)
+    .help()
+    .argv;
+
+module.exports = { argv };
\ No newline at end of file
diff --git a/db/data.json b/db/data.json
new file mode 100644
index 0000000..9868eea
--- /dev/null
+++ b/db/data.json
@@ -0,0 +1 @@
+[{"descripcion":"Salir de la casa","completado":false},{"descripcion":"Pasear al perro","completado":false}]
\ No newline at end of file
diff --git a/package-lock.json b/package-lock.json
new file mode 100644
index 0000000..f11e7af
--- /dev/null
+++ b/package-lock.json
@@ -0,0 +1,203 @@
+{
+    "name": "04-por-hacer",
+    "version": "1.0.0",
+    "lockfileVersion": 1,
+    "requires": true,
+    "dependencies": {
+        "@types/color-name": {
+            "version": "1.1.1",
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+        },
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+            "version": "5.0.0",
+            "resolved": "https://registry.npmjs.org/ansi-regex/-/ansi-regex-5.0.0.tgz",
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+        },
+        "ansi-styles": {
+            "version": "4.2.1",
+            "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-4.2.1.tgz",
+            "integrity": "sha512-9VGjrMsG1vePxcSweQsN20KY/c4zN0h9fLjqAbwbPfahM3t+NL+M9HC8xeXG2I8pX5NoamTGNuomEUFI7fcUjA==",
+            "requires": {
+                "@types/color-name": "^1.1.1",
+                "color-convert": "^2.0.1"
+            }
+        },
+        "camelcase": {
+            "version": "5.3.1",
+            "resolved": "https://registry.npmjs.org/camelcase/-/camelcase-5.3.1.tgz",
+            "integrity": "sha512-L28STB170nwWS63UjtlEOE3dldQApaJXZkOI1uMFfzf3rRuPegHaHesyee+YxQ+W6SvRDQV6UrdOdRiR153wJg=="
+        },
+        "cliui": {
+            "version": "6.0.0",
+            "resolved": "https://registry.npmjs.org/cliui/-/cliui-6.0.0.tgz",
+            "integrity": "sha512-t6wbgtoCXvAzst7QgXxJYqPt0usEfbgQdftEPbLL/cvv6HPE5VgvqCuAIDR0NgU52ds6rFwqrgakNLrHEjCbrQ==",
+            "requires": {
+                "string-width": "^4.2.0",
+                "strip-ansi": "^6.0.0",
+                "wrap-ansi": "^6.2.0"
+            }
+        },
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+            "version": "2.0.1",
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+            }
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+        },
+        "colors": {
+            "version": "1.4.0",
+            "resolved": "https://registry.npmjs.org/colors/-/colors-1.4.0.tgz",
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+        },
+        "decamelize": {
+            "version": "1.2.0",
+            "resolved": "https://registry.npmjs.org/decamelize/-/decamelize-1.2.0.tgz",
+            "integrity": "sha1-9lNNFRSCabIDUue+4m9QH5oZEpA="
+        },
+        "emoji-regex": {
+            "version": "8.0.0",
+            "resolved": "https://registry.npmjs.org/emoji-regex/-/emoji-regex-8.0.0.tgz",
+            "integrity": "sha512-MSjYzcWNOA0ewAHpz0MxpYFvwg6yjy1NG3xteoqz644VCo/RPgnr1/GGt+ic3iJTzQ8Eu3TdM14SawnVUmGE6A=="
+        },
+        "find-up": {
+            "version": "4.1.0",
+            "resolved": "https://registry.npmjs.org/find-up/-/find-up-4.1.0.tgz",
+            "integrity": "sha512-PpOwAdQ/YlXQ2vj8a3h8IipDuYRi3wceVQQGYWxNINccq40Anw7BlsEXCMbt1Zt+OLA6Fq9suIpIWD0OsnISlw==",
+            "requires": {
+                "locate-path": "^5.0.0",
+                "path-exists": "^4.0.0"
+            }
+        },
+        "get-caller-file": {
+            "version": "2.0.5",
+            "resolved": "https://registry.npmjs.org/get-caller-file/-/get-caller-file-2.0.5.tgz",
+            "integrity": "sha512-DyFP3BM/3YHTQOCUL/w0OZHR0lpKeGrxotcHWcqNEdnltqFwXVfhEBQ94eIo34AfQpo0rGki4cyIiftY06h2Fg=="
+        },
+        "is-fullwidth-code-point": {
+            "version": "3.0.0",
+            "resolved": "https://registry.npmjs.org/is-fullwidth-code-point/-/is-fullwidth-code-point-3.0.0.tgz",
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+        },
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+            "version": "5.0.0",
+            "resolved": "https://registry.npmjs.org/locate-path/-/locate-path-5.0.0.tgz",
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+            "requires": {
+                "p-locate": "^4.1.0"
+            }
+        },
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+            "version": "2.2.2",
+            "resolved": "https://registry.npmjs.org/p-limit/-/p-limit-2.2.2.tgz",
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+            "requires": {
+                "p-try": "^2.0.0"
+            }
+        },
+        "p-locate": {
+            "version": "4.1.0",
+            "resolved": "https://registry.npmjs.org/p-locate/-/p-locate-4.1.0.tgz",
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+            "requires": {
+                "p-limit": "^2.2.0"
+            }
+        },
+        "p-try": {
+            "version": "2.2.0",
+            "resolved": "https://registry.npmjs.org/p-try/-/p-try-2.2.0.tgz",
+            "integrity": "sha512-R4nPAVTAU0B9D35/Gk3uJf/7XYbQcyohSKdvAxIRSNghFl4e71hVoGnBNQz9cWaXxO2I10KTC+3jMdvvoKw6dQ=="
+        },
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+        },
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+            "version": "2.1.1",
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+            "integrity": "sha1-jGStX9MNqxyXbiNE/+f3kqam30I="
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+        "require-main-filename": {
+            "version": "2.0.0",
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+        },
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+            "resolved": "https://registry.npmjs.org/set-blocking/-/set-blocking-2.0.0.tgz",
+            "integrity": "sha1-BF+XgtARrppoA93TgrJDkrPYkPc="
+        },
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+                "is-fullwidth-code-point": "^3.0.0",
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+            }
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+            "version": "2.0.0",
+            "resolved": "https://registry.npmjs.org/which-module/-/which-module-2.0.0.tgz",
+            "integrity": "sha1-2e8H3Od7mQK4o6j6SzHD4/fm6Ho="
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+            "requires": {
+                "ansi-styles": "^4.0.0",
+                "string-width": "^4.1.0",
+                "strip-ansi": "^6.0.0"
+            }
+        },
+        "y18n": {
+            "version": "4.0.0",
+            "resolved": "https://registry.npmjs.org/y18n/-/y18n-4.0.0.tgz",
+            "integrity": "sha512-r9S/ZyXu/Xu9q1tYlpsLIsa3EeLXXk0VwlxqTcFRfg9EhMW+17kbt9G0NrgCmhGb5vT2hyhJZLfDGx+7+5Uj/w=="
+        },
+        "yargs": {
+            "version": "15.1.0",
+            "resolved": "https://registry.npmjs.org/yargs/-/yargs-15.1.0.tgz",
+            "integrity": "sha512-T39FNN1b6hCW4SOIk1XyTOWxtXdcen0t+XYrysQmChzSipvhBO8Bj0nK1ozAasdk24dNWuMZvr4k24nz+8HHLg==",
+            "requires": {
+                "cliui": "^6.0.0",
+                "decamelize": "^1.2.0",
+                "find-up": "^4.1.0",
+                "get-caller-file": "^2.0.1",
+                "require-directory": "^2.1.1",
+                "require-main-filename": "^2.0.0",
+                "set-blocking": "^2.0.0",
+                "string-width": "^4.2.0",
+                "which-module": "^2.0.0",
+                "y18n": "^4.0.0",
+                "yargs-parser": "^16.1.0"
+            }
+        },
+        "yargs-parser": {
+            "version": "16.1.0",
+            "resolved": "https://registry.npmjs.org/yargs-parser/-/yargs-parser-16.1.0.tgz",
+            "integrity": "sha512-H/V41UNZQPkUMIT5h5hiwg4QKIY1RPvoBV4XcjUbRM8Bk2oKqqyZ0DIEbTFZB0XjbtSPG8SAa/0DxCQmiRgzKg==",
+            "requires": {
+                "camelcase": "^5.0.0",
+                "decamelize": "^1.2.0"
+            }
+        }
+    }
+}
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..82a79a4
--- /dev/null
+++ b/package.json
@@ -0,0 +1,15 @@
+{
+    "name": "04-por-hacer",
+    "version": "1.0.0",
+    "description": "",
+    "main": "index.js",
+    "scripts": {
+        "test": "echo \"Error: no test specified\" && exit 1"
+    },
+    "author": "Adrián Antón",
+    "license": "ISC",
+    "dependencies": {
+        "colors": "^1.4.0",
+        "yargs": "^15.1.0"
+    }
+}
diff --git a/por-hacer/por-hacer.js b/por-hacer/por-hacer.js
new file mode 100644
index 0000000..cf3793e
--- /dev/null
+++ b/por-hacer/por-hacer.js
@@ -0,0 +1,85 @@
+const fs = require('fs');
+
+
+let listadoPorHacer = [];
+
+const guardarDB = () => {
+    let data = JSON.stringify(listadoPorHacer);
+
+    fs.writeFile('db/data.json', data, (err) => {
+        if (err) throw new Error('No se pudo grabar', err);
+        console.log('The file has been saved!');
+    });
+}
+
+
+const cargarDB = () => {
+    try {
+        listadoPorHacer = require('../db/data.json');
+    } catch (error) {
+        listadoPorHacer = [];
+    }
+};
+
+const crear = (descripcion) => {
+    cargarDB();
+    let porHacer = {
+        descripcion: descripcion,
+        completado: false
+    };
+
+    listadoPorHacer.push(porHacer);
+    guardarDB();
+    return porHacer;
+};
+
+const getListado = () => {
+    cargarDB();
+    return listadoPorHacer;
+};
+
+const actualizar = (descripcion, completado = true) => {
+    cargarDB();
+    let index = listadoPorHacer.findIndex(tarea => {
+        return tarea.descripcion === descripcion;
+    });
+
+    if (index >= 0) {
+        listadoPorHacer[index].completado = completado;
+        guardarDB();
+        return true;
+    } else {
+        console.log('Tarea no encontrada:', descripcion);
+        return false;
+    }
+
+};
+
+const borrar = (descripcion) => {
+    cargarDB();
+    // let index = listadoPorHacer.findIndex(tarea => {
+    //     return tarea.descripcion === descripcion;
+    // });
+    // if (index >= 0) {
+    //     listadoPorHacer.splice(index, 1);
+    //     guardarDB();
+    //     return true;
+    // } else {
+    //     console.log('Tarea no encontrada:', descripcion);
+    //     return false;
+    // }
+    let nuevoListado = listadoPorHacer.filter(tarea => {
+        return tarea.descripcion !== descripcion;
+    });
+
+    if (nuevoListado.length === listadoPorHacer.length) {
+        return false;
+    } else {
+        listadoPorHacer = nuevoListado;
+        guardarDB();
+        return true;
+    }
+
+};
+
+module.exports = { crear, getListado, actualizar, borrar };
\ No newline at end of file