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
To find out if a command exists on a Unix/Linux system, you can use the which or the type command. Both commands search for the specified command in the directories listed in the system’s $PATH environment variable. Here’s how to use the which command: which command_name Replace command_name with the name of the command you … Read more
Setting up a chroot jail for Nginx on Linux can help to increase the security of your web server. A chroot jail is a way to isolate a process and its children from the rest of the system by restricting their access to a specific directory tree. Here are the steps to set up a … Read more
In Linux, you can set or change the library path using the LD_LIBRARY_PATH environment variable. This variable is used by the dynamic linker/loader to locate shared libraries at runtime. Here’s how to set or change the library path: To set the library path, open a terminal and enter the following command: export LD_LIBRARY_PATH=/path/to/library:$LD_LIBRARY_PATH Replace /path/to/library … Read more
You can use tc to shape the outgoing HTTP traffic (i.e., port 80) on a Linux machine. Here is an example of how to do it: Identify the network interface that is connected to the internet. You can use the ifconfig command to get a list of all network interfaces and their IP addresses. Create … Read more
To verify the PGP signature of a tarball file in UNIX/Linux, you can follow these steps: Download both the tarball and the PGP signature file from the source. Import the signer’s public key into your keyring. For example, if the signer’s key is available on a keyserver, you can import it using the following command: … Read more
If you are using the deny directive in your Nginx configuration to block access to certain IP addresses or ranges, you may find that your custom error page for HTTP 403 Forbidden errors is not being displayed for denied requests. This is because when a request is denied by the deny directive, Nginx returns a … Read more