PHP developers and web server admins can use the phpinfo function to quickly see information about their installation of PHP. This can assist in debugging, seeing what version of PHP is installed, or seeing various configuration options.

On Linux systems, it's common to make a phpinfo.php page after installing a LAMP server or LEMP server to make sure that PHP is working and to verify settings.

In this tutorial, we'll guide you through the creation of a phpinfo.php page on your own system, as well as how to access this file afterwards.

• How to create phpinfo.php page

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Bash one-liners can reduce workload, automate something quickly and put the power of ultimate system control in your hands. Over time, you will likely learn to write more complex one-liners and some of the things you end up writing as a seasoned professional will be nearly in-parsible by a beginner. That said, the Bash command and development language is highly structured - and relatively easy to understand - once you know about the in and outs. It really is like becoming proficient in a foreign language.

In this tutorial you will learn:

• How to write more advanced Bash one-liner commands and scripts
• Understand how to combine various commands into one-liner scripts
• Understand how exit codes from one command can affect other commands when using && and ||
• Understand how input from a command can be modified and then be used by the next command
• Usage and real-life like examples of more advanced Bash one-liners

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Bash is a varied shell interface with many programming options, and a rich instructional language. It is easy to miss Bash features and dynamics, so this series introduces a number of tips, tricks, examples and gotchas when it comes to using Bash. For the first two article in this series, please see our article Useful Bash command line tips and tricks examples part 2 and Useful Bash command line tips and tricks examples part 3.

In this tutorial series you will learn:

• Useful Bash command line tips, tricks and methods
• How to interact with the Bash command line in an advanced manner
• How to sharpen your Bash skills overall and become a more proficient Bash user

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If you read our previous linux subshells for beginners with examples article, or are experienced with subshells already, you know that subshells are a powerful way to manipulate Bash commands inline, and in a context sensitive manner.

In this tutorial you will learn:

• How to create more advanced subshell commands
• Where you can employ more advanced subshells in your own code
• Examples of more advanced subshell commands

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Making use of subshells in Bash provides you with an ability to generate context sensitive information from right within your Bash command. For example, if you want to modify a text string right inside an echo statement, then this can be done easily with subshells.

In this tutorial you will learn:

• How to use employ the use of subshells in Bash
• How to use subshells to obtain context sensitive information
• Basic Bash subshell usage examples

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In this series we are exploring various tips, tricks and Bash command line examples which will help you become a more advanced Bash user and coder. Bash provides a rich scripting and coding language which puts the power back in the hands of the user and developer. Bash also allows you to learn as you go along, thereby making it a more enjoyable experience. For the first article in our series, please see our article Useful Bash command line tips and tricks examples part 1.

In this tutorial series you will learn:

• Useful Bash command line tips, tricks and methods
• How to interact with the Bash command line in an advanced manner
• How to sharpen your Bash skills overall and become a more proficient Bash user

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You may already be versed in debugging Bash scripts (see How to Debug Bash Scripts if you are not familiar with debugging Bash yet), yet how to debug C or C++? Let’s explore.

GDB is a long-standing and comprehensive Linux debugging utility, which would take many years to learn if you wanted to know the tool well. However, even for beginners, the tool can be very powerful and useful when it comes to debugging C or C++.

For example, if you’re a QA engineer and would like to debug a C program and binary your team is working on and it crashes, you can use GDB to obtain a backtrace (a stack list of functions called - like a tree - which eventually led to the crash). Or, if you are a C or C++ developer and you just introduced a bug into your code, then you can use GDB to debug variables, code and more! Let’s dive in!

In this tutorial you will learn:

• How to install and use the GDB utility from the command line in Bash
• How to do basic GDB debugging using the GDB console and prompt
• Learn more about the detailed output GDB produces

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If you are new to xargs, or do not know what xargs is yet, please read our xargs for beginners with examples first. If you are already somewhat used to xargs, and can write basic xargs command line statements without looking at the manual, then this article will help you to become more advanced with xargs on the command line, especially by making it multi-threaded.

In this tutorial you will learn:

• How to use xargs -P (multi-threaded mode) from the command line in Bash
• Advanced usage examples using multi-threaded xargs from the command line in Bash
• A deeper understanding of how to apply xargs multi-threaded to your existing Bash code

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The need to compare strings in a Bash script is relatively common and can be used to check for certain conditions before proceeding on to the next part of a script. A string can be any sequence of characters. To test if two strings are the same, both strings must contain the exact same characters and in the same order. It could be a word or a whole sentence. For example, string one is equal to string one but is not equal to string two. Get the idea?

In this guide, we'll show you how to compare strings in the Bash shell on a Linux system. We'll show this in the context of a simple if/else Bash script so you can see how testing for this condition would work when developing scripts, but we'll also show how this same comparison can be done in the command line terminal.

• How to compare strings in Bash
• Example if/else Bash scripts that compare strings

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The date command on a Linux system is a very versatile command that can be used for many functions. Among them is the ability to calculate a file's creation date, last modified time, etc. This can be built into a script, used for scheduling, or just used to obtain basic information about a file or directory on the system.

The date command can also handle addition and subtraction arithmetic to help calculate dates and times. It uses Unix's epoch time as a base of reference, which is 00:00:00 UTC on January 1, 1970. From this date, it can assign a timestamp based on the number of seconds something occurred before or after it.

These timestamps are great for calculation, but hardly usable for people. It'd take a machine to know that Thu 02 Jun 2016 12:59:59 PM UTC translates to 1464872399. In this guide, we'll explain how to convert a timestamp to a human readable date and vice versa.

• How to convert a timestamp to date

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Suppose we write a script which spawns one or more long running processes; if said script receives a signal such as SIGINT or SIGTERM, we probably want its children to be terminated too (normally when the parent dies, the children survives). We may also want to perform some cleanup tasks before the script itself exits. To be able to reach our goal, we must first learn about process groups and how to execute a process in background.

In this tutorial you will learn:

• What is a process group
• The difference between foreground and background processes
• How to execute a program in background
• How to use the shell wait built in to wait for a process executed in background
• How to terminate child processes when the parent receives a signal

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Have you or one of your MySQL users forgotten the password to a MySQL account? It's very easy to reset a MySQL user password on Linux, and we'll show you the commands and step by step instructions below.

Changing the MySQL root password is a bit more involved, so we've written a separate guide on how to change MySQL root password.

• How to change MySQL user password

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When coding Bash scripts - especially when developing scripts for functionality testing - we sometimes need to generate a random number or random input. These numbers may also need to be within a specific range. This article will teach you how to perform random number generation in Bash.

In this tutorial you will learn:

• How to generate random numbers in Bash
• How to generate random numbers is a specific range
• Examples demonstrating random number generation in Bash

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When using random numbers in Bash, the question of random entropy will sooner or later come up. This article will help you understand what entropy is, how it can be modified and optimized in Bash, and how it will affect random number generation.

In this tutorial you will learn:

• How to generate random entropy in Bash
• How to pre-seed the random number generator in Bash
• Examples demonstrating random entropy generation in Bash

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Using xargs, described in the Linux xargs manual as a tool which builds and execute command lines from standard input, once can exert a significant amount of additional power over any other command executed on the Bash command line. Basically, xargs will take the output from any other tool, and use that as it’s own input for further processing and action (hence the reference to executing command lines in the manual). If this is your first few weeks or months with xargs, or you are only just starting, this is the best place for you to get into xargs.

In this tutorial you will learn:

• How to use xargs from the command line in Bash
• How xargs works, what it does, and how to use it well
• Basic usage examples using xargs from the command line in Bash

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