Tutorials

Step-by-step technical guides on Docker, Linux, Python, Go, and more.

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1 min read

How to Trim String in JavaScript ?

With javascript if you need to remove the spaces on left and right you can use trim. If you need to trim only the left side of the string use replace with a regex, ex: str.replace(/^s+/,'');. Check this article for more details

2 min readIntermediate

Flask: How to Test file upload

Example on how to test file upload using flask client. Check here how to do a request using the FlaskClient to simulare a file upload. You need to put a tuple in the request payload with the data types: (, ) ex. file': (StringIO('my file contents'), 'test_file.txt'). Check here for a full example

2 min read

Ubuntu 18.04: Connect to WiFi via CLI

Debian/Ubuntu linux uses wpa_supplication to support WPA/WPA2 connections. In this tutorial we are going to connect to the Wi-Fi using the command line. See how to do it.

1 min readIntermediate

Vue.js: Show First and Last Array Elements

Sometimes in templates you need to show the first or last element of an array or you need to close a html tag on the last item while you are doing an iteration. You can just use Vue protototype to extend it: Vue.prototype.$last = function (item, list) { return item === list[list.length - 1] }. Check here for full details.

2 min readIntermediate

How to transfer files over the network using Netcat

Netcat is a helpful tool when you are in a hurry to transfer files between machines. Om this tutorial we will explain how to receive and send files using netcat. For receive: nc -l -p 9999 > received_file.txt, For sending: nc 192.168.0.1 9999 < received_file.txt. Check here how to compress and uncompress data using netcat.

1 min read

How to Show or Hide Files in Finder (OSX)

If you want to show or hide files in finder you can use defaults command. To enable it use defaults write com.apple.finder AppleShowAllFiles TRUE. You need to kill Finder, check here for more details

5 min readBeginner

Test SSL / TLS with GnuTLS from the Command Line

In this tutorial we are going to use gnutls-cli from the command line to test SSL/TLS connection. This command could be useful to test a web or an imap server. Install it with: sudo apt -y install gnutls-bin. Example of usage: gnutls-cli -d 5 imap.gmail.com -p 993

2 min readBeginner

Javascript: How to remove a specific element from an array?

In this small tutorial we will give example on how to remove a specific element from an array with javascript. Code example: var index = array.indexOf(5); if (index > -1) { array.splice(index, 1); }

4 min readAdvanced

PMP Exam Preparation Tips and Questions

The Project Management Professional (PMP) is the most important industry-recognized certification. We recommend Rita Mulcahy's book, Andy Crow study PMP guides and Kin Heldmen study guide. We also provide links to free PMP questions. Finally remember the PMBok is your bible! Read here for more details.

1 min readBeginner

JavaScript: Get Dropdown Selected Value

We will explain hot to retrieve the selected element using javascript. e.options[e.selectedIndex].value will return the value of the selected element where e is the variable obtained with document.getElementById("selector"). Check here a full jQuery example also. Read our tutorial for more details.