To configure OpenSSH to listen on an IPv6 address, you need to modify the sshd_config file. Here’s how to do it: Open the sshd_config file: sudo vi /etc/ssh/sshd_config Find the line that begins with ListenAddress: If the line exists, you can skip this step. If not, add the following line: ListenAddress :: This line tells … Read more

To rename files in Linux, you can use the mv command. Here are some examples of how to use mv to rename files: Rename a single file: To rename a single file, simply use the mv command followed by the current file name and the new file name. For example, to rename a file named … Read more

grep is a powerful command-line tool that allows you to search for text patterns in files using regular expressions (regex). Regular expressions are a powerful way to describe patterns of text, allowing you to search for much more than just literal strings. Here are some examples of how to use regular expressions with grep: Match … Read more

To extract files from a compressed tar archive on Linux, you can use the tar command with the xvf options. The x option specifies that you want to extract files, the v option stands for “verbose” and will show you the names of the files being extracted, and the f option is used to specify … Read more

To count the number of lines in a text file that contain a specific string or word on a Linux or Unix system, you can use the grep command with the -c option. The general syntax for the grep command is: grep [OPTIONS] PATTERN [FILE…] where: OPTIONS: Any options you want to use with the … Read more

To truncate a large text file in UNIX or Linux, you can use the “truncate” command. The general syntax for the “truncate” command is: truncate [OPTION]… SIZE FILE… where: OPTION: Any options you want to use with the command (e.g., -s for specifying the size in bytes, -c for not creating the file if it … Read more

If you want to move a file that starts with a dash (-), you can use the following command: mv — -filename destination The double dash — tells the mv command that there are no more command line options, and that the remaining arguments are file names. For example, if you want to move a … Read more

Keepalived is a daemon that provides simple and robust facilities for load balancing and high-availability to Linux based infrastructures. It uses the VRRP (Virtual Router Redundancy Protocol) protocol to provide a highly available IP address to be used as a default gateway by clients. If the primary node goes down, Keepalived will automatically transfer the … Read more

In UNIX and Linux, file permissions are defined by three sets of permissions for three types of users: the owner, the group, and others. These permissions are read (r), write (w), and execute (x). In addition to these basic permissions, there is a special type of file permission called setuid (short for “set user ID”). … Read more

To install and configure Nginx as a reverse proxy and load balancer on CentOS or Red Hat, you can follow these steps: Install the EPEL repository if it is not already installed on your system. EPEL provides additional packages that are not available in the official CentOS or Red Hat repositories. You can install it … Read more