today's howtos
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How to Install PHP 8.2, 8.1, 8.0, 7.4 on CentOS Stream EL9 or EL8
PHP (Hypertext Preprocessor) is a widely-used, open-source programming language particularly suited for web development. It can be easily integrated into the CentOS stream system, providing many benefits.
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How to Install NetBox on Rocky Linux 9
NetBox is an Infrastructure Resource Modelling (IRM) software designed for network automation and infrastructure engineering.
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How to Install Wireguard VPN on Rocky Linux 9
Wireguard is an open-source VPN protocol alternative to IPSec, IKEv2, and OpenVPN.
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How to Kick Out SSH Users from the Linux System
As a sysadmin, when you are working on a remote system or server, multiple users might be accessing the same system via SSH simultaneously.
Active users can gently disconnect from the server by issuing the “exit” command in the terminal once they are done with their work.
However, some careless users fail to logout and leave the session running in the background, which will logout the user only if you configured SSH to automatically kick out the user after a certain amount of idle time or the user logs out manually.
In this quick tutorial, you will learn how to kick out SSH-connected users from the target system from your end as a sysadmin.
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How to Rename a Batch of Files in Linux
The “mv” command is generally used in Linux to rename a single file. But sometimes, it requires to rename a batch of files. Many utilities exist in Linux to do this task. Some of them are “rename”, “imv”, “qmv”, “mmv”, etc. These are not installed in Linux by default. These utilities are required to install to rename a batch of files. The batch of files can also be removed using the built-in “mv” command with the loop or other commands. The different ways to rename a batch of files in Linux are shown in this tutorial.
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How to Use the Sed Command to Replace a String in a File
The full form of the “sed” command is a stream editor. This command is a very powerful command of the Linux operating system and it is used for various purposes. One of the common uses of this command is to find and replace one or more string values of a file. The particular content of a file can be replaced by this command without opening the file. The “sed” command supports regular expression. The specific string value can be searched inside a file based on the regular expression which is defined with this command. The different ways of searching and replacing the particular string in a file using the “sed” command are shown in this tutorial.
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How to Use the Curl Command in Bash
The full form of curl is the Client URL. It is a command-line tool that is used to transfer the data from or to any server using a particular protocol such as HTTP, HTTPS, FTP, TELNET, LDAP, etc. A specific URL is used by this tool to communicate with a web server or the application server to get or send the data. It can be used directly from the terminal or by using any script. Downloading the files from the server, debugging, endpoint testing, and other tasks can be done using curl. The different uses of the curl command are shown in this tutorial.
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How to Use the Bash “If –Z” and “If –N” Statements to Test the String
The “if” statement is used in Bash for conditional branching like in other programming languages. The “if” statement can be used to check the different conditions in Bash. The different types of comparison operators, logical operators, and options are used with the “if” statement for testing. The uses of the “-z” and “-n” option to test the string values using the “if” statement in Bash are shown in this tutorial.
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Bash Built-In Commands
Many built-in commands exist in Bash to perform different types of tasks. Bash has no built-in function like other programming languages. But the tasks of the built-in functions can be done easily using the different types of built-in commands of Bash. Bash has some special built-in commands and some inherited built-in commands which are inherited from the shell commands. The purposes of the most commonly used built-in commands of Bash and the uses of some built-in commands are described in this tutorial.
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Bash PATH Tutorial
The PATH is an environment variable that is used to store the location of the resources that contain executable files on the Linux operating system. The PATH is defined using slash(/) and alphanumeric characters. Two types of PATH can be defined in Linux. One is an absolute path and the other is a relative path. The full location of a particular file or directory or file system is defined by an absolute path. The location that is relative to the current working directory is defined by the relative path. The $PATH variable mainly contains the location of those directories that execute frequently such as/bin, /usr/bin, /usr/local/bin, etc.
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Bash Pipe Tutorial
Normally, we get the output of any command into the terminal. Sometimes, we need to send the output of the command as the input of another command. This task can be done by executing the commands multiple times. But this task can be done easily using a pipe command that executes two or more commands at a time in Linux where the output of the one command is the input of the next command. The ‘|’ operator is used for piping. The uses of the pipe command are described in this tutorial.
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How to Use the Stdin, Stderr, and Stdout Streams in Bash
Three streams are opened when the Linux operating system starts. These are stdin, stdout, and stderr. The full form of stdin is standard input which is used to take an input from the user. The full form of stdout is the standard output which is used to store the output of the command into the stdout stream. The full form of stderr is the standard error which is used to store the error message that is generated from any command into the data stream. The uses of these streams are shown in this tutorial. The corresponding numerical identifier values of stdin, stdout, and stderr are 0, 1, and 2.
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A Beginner's Guide to Arduino Inputs/Outputs!
Becky Stern is back with another of her excellent Digi-Key electronics tutorials. In this one, she covers the basics of Arduino I/O, both analog and digital.