To encrypt a backup tape using tar and OpenSSL in Linux/UNIX, you can follow these steps: Create a backup archive using tar command. For example, to create a backup of /home directory, run: tar czvf /dev/st0 /home This will create a compressed backup of the /home directory and write it to /dev/st0 tape device. Use … Read more

In Bash, you can use parameter expansion to trim leading white space from input variables. Here’s an example: #!/bin/bash input=” hello world” trimmed=${input#”${input%%[![:space:]]*}”} echo “Original input: \”$input\”” echo “Trimmed input: \”$trimmed\”” In this example, the input variable is assigned a value with leading white space. The trimmed variable uses parameter expansion to remove the leading … Read more

In Lighttpd, you can use the mod_setenv module to send custom headers to the client. Here’s how you can do it: Enable the mod_setenv module: If the mod_setenv module is not already enabled, you’ll need to enable it in your Lighttpd configuration file. Add the following line to the file: server.modules += (“mod_setenv”) Set the … Read more

Upgrading Red Hat Enterprise Linux (RHEL) to version 5.5 involves a few steps. Here is a general procedure to upgrade RHEL to version 5.5: Backup your system: Before you upgrade your system, make sure you have a backup of your system in case anything goes wrong. Update your current version: Make sure that your current … Read more

When you’re editing a file in Vim/Vi and you need to save the changes to the file, but you don’t have the necessary permissions, you can use the :w !sudo tee % command to save the file with root permission. Here are the steps: Open the file with Vim/Vi: Open the file you want to … Read more

To set up a reverse proxy with SSL (Secure Sockets Layer) on Nginx, you’ll need to follow these steps: Install and configure Nginx: First, you’ll need to install Nginx on your server and configure it as a reverse proxy. You can follow the official Nginx installation guide for your Linux distribution to install Nginx. Generate … Read more

To move a directory up one level in Linux/Unix, you can use the mv command with the .. syntax. Here’s an example: Let’s say you have a directory named mydir that you want to move up one level: /home/user/mydir/ To move mydir up one level to /home/user/, you can use the following command: mv mydir/ … Read more

To check if a function exists or not in Bash shell, you can use the type command with the -t option. Here’s an example: if [ $(type -t myfunction) = function ]; then echo “myfunction is defined” else echo “myfunction is not defined” fi In this example, we use the type command with the -t … Read more

You can use the rpm command to view the scripts that run when you install an RPM package. RPM packages can contain scripts that run during the installation, upgrade, or removal of the package. Here’s how to view the installation scripts for an RPM package: rpm -qp –scripts package.rpm Replace package.rpm with the name of … Read more

You can use the size command on a binary object file to display the section sizes and the total size of the text and data segments. The size command displays the size of all the sections in the binary object file, along with their virtual addresses and names. By looking at the size of the … Read more