Regular Expressions

In this guide we are going to learn how to use Regular Expressions (regex) to match any pattern or text. This is often used in text editors, CLI commands(like grep or awk) and programming languages. What is regex? Regex are patterns used to match/find strings in a text. You might think that you can use

Using grep command in Linux

What is grep ? Grep stands for Global Regular Expression Print. Grep utility is usually used to find lines in a file/files containing particular strings and substrings. Grep comes preinstalled on any modern Linux distribution, so we can start using it without having to install anything. Before we start looking at usage examples of grep

Using awk command in Linux

What is awk? Awk is a programming language which has loops, arrays, functions etc., but nowadays mostly used only for “one-liners”. Awk is not used for creating complex programs, but it  is great when we need to add some additional functionality to our standard Linux commands. We will have a look at some of its

ifconfig missing in Ubuntu 18.04

Command ‘ifconfig’ not found in Ubuntu 18.04 ifconfig utility has been deprecated and completely removed in Ubuntu 18.04 If you try to run ifconfig you will get error: administrator@ubuntu:~$ ifconfig Command 'ifconfig' not found, but can be installed with: sudo apt install net-tools You may install ifconfig utility by running sudo apt install net-tools or you

CallerID Lookup Source in FreePBX

How to display a name instead of CallerID for a call coming from PSTN CID Lookup Source is a feature that allows us to display names instead of CallerID numbers for incoming calls from PSTN. For example, you might want to add your colleagues’ names and cell phone numbers to the list, so when they

How to enable call recording in FreePBX

Call recording in FreePBX. FreePBX allows us to enable call recording without any additional hardware and licenses. It also has a web interface for playback, so we can easily find the recordings and listen to them using only built-in tools. In this post we are going to look at the call recording configuration steps for

How to configure DHCP server on Aruba switches

The configuration of DHCP server on Aruba switches is pretty similar to the configuration of DHCP server on Cisco switches, except that Aruba switches require  dhcp-server explicitly enabled on an interface. First, we have to configure L3 interface on our switch, the snippet below shows how to assign IP address(192.168.1.1) to VLAN 1. Now that