The Linux command line has many tools that we can use to extract information from text files. In this tutorial, we’ll use a few different methods to extract email addresses from a text file on Linux.
scripting
C++ code on how to read characters from a file
This tutorial will show you a small example of C++ code on how to read a characters from a file, as well as to count the number lines that any particular file consist of. We will be creating the script and compiling the C++ on a Linux system. All distros will work the same, provided you have the G++ compiler installed, which we will cover as well.
logrotate command in Linux with examples
In Linux, many applications and system services will store log files. These log files give a Linux administrator insight into how their system is performing, and are invaluable when troubleshooting issues. However, log files can get unwieldy very quickly. For example, if your web server software logs every visit to your website, and you get thousands of viewers per day, there will be way too much information to feasibly squeeze into one text file.
usermod command in Linux with examples
The usermod command in Linux is used to modify user accounts. In particular, it’s used for changing various attributes for accounts that are already created, since a separate command is used when creating a brand new account on Linux.
Cat command in Linux with examples
The cat command in Linux is our primary tool for viewing the contents of text files on Linux systems. When using or administrating a Linux system, you are usually confronted with a command line. There are no graphical aids such as mouse or windows to help you navigate through directories or edit files.
Watch command in Linux with Examples
Have you ever had to sit at a Linux terminal and repeatedly type the same command while waiting for a different result? A common example from personal experience would be typing the ls command when waiting for a certain file to appear in a directory, such as when a running Bash script is expected to generate a file. For a situation like that is exactly why we have the watch command in Linux.
Addition and subtraction arithmetics with Linux date command
The date command on Linux can be used to see the current date and time, but we can also use addition and subtraction arithmetic with the command to extend its functionality. For example, instead of seeing the current date, we can see the date and time from five days ago, five years in the future, etc. The possibilities here are endless.
C++ function to calculate Fibonacci number sequence
In this artcile you will learn how calculate Fibonacci sequence with using C++ function. The Fibonacci sequence starts with 0 and 1 where the the following number is always a sum of the two preceding numbers. For example, 0,1,1,2,3,5,8 and so on.
In this tutorial you will learn:
- How to compile Fibonacci C++ program
- How to run Fibonacci C++ program
Check domain name availability with bash and whois
If you’ve ever tried to come up with a catchy domain name, you know how annoying it can be to keep checking to see if a certain name is available. Fortunately, on Linux we can make the task a little easier on us by using the whois command. When a domain is available, the output from whois will let us know that it’s not able to find any information for that domain.
It’s easy enough then to put this functionality into a Bash script, which helps to automate checking lots of different TLDs (Top Level Domains, like .com, .net, .org, etc).
In this guide, we’ll show how to check domain name availability from the command line on Linux. Then, we’ll give you a simple Bash script that you can copy onto your own system and check for lots of domains at once. Read on to learn how.
In this tutorial you will learn:
- How to install whois on major Linux distros
- How to check for domain name availability with whois command
- Bash script for checking domain name availability
Rename all file names from uppercase to lowercase characters
As a Linux user, you’re likely already familiar with using the mv command to rename a file on a Linux system. The task becomes a little more difficult when you need to rename multiple files at the same time on Linux.
One of the most common batch renaming jobs that are performed is to change all file names to lowercase letters. There are several different ways to do this on Linux. One way is with the native mv utility and a bit of Bash scripting, and the other methods involve the rename and mmv tools, which may or may not already be installed on your Linux distro by default.
In this guide, we’ll go over various command line examples to rename all files from uppercase to lowercase letters on Linux. Some commands will work only for files, some for directories, and some commands work recursively. Take a look at all the different examples below to decide which command(s) to use that would best suit your needs.
In this tutorial you will learn:
- How to rename all files from uppercase to lowercase using mv, rename, or mmv commands
- How to install rename and mmv on major Linux distros