In Bash shell, you can generate random numbers using the built-in “RANDOM” variable or the “shuf” command. Here’s how to do it: Using the RANDOM variable: Use the “$RANDOM” variable to generate a random number between 0 and 32767: echo $RANDOM This will output a random number each time you run the command. Use the … Read more

In Linux or UNIX, you can run multiple X sessions (graphical sessions) simultaneously by using different virtual terminals (VTs). Here’s how to do it: Press “Ctrl + Alt + F2” (or any other function key from F2 to F7) to switch to the second virtual terminal. This opens a new login prompt. Log in with … Read more

To display only today’s files in Linux or UNIX, you can use the “find” command with the “-daystart” and “-ctime” options. Here’s how to do it: find /path/to/files -daystart -ctime 0 This command searches for files in the specified directory (/path/to/files in the example) that were created or modified within the last 24 hours. The … Read more

Memory leaks can be a common problem for long-running programs, and they can cause performance issues and system crashes over time. Fortunately, Linux provides tools to check for memory leaks in programs. Here are some steps to do so: Install the valgrind tool: Valgrind is a popular tool for detecting memory leaks and other memory-related … Read more

OpenBSD includes support for mounting NTFS file systems, but you need to install the ntfs-3g package to mount them. Here’s how to mount an NTFS file system on OpenBSD: Install the ntfs-3g package: The ntfs-3g package provides the tools necessary to mount NTFS file systems on OpenBSD. You can install it using the package manager … Read more

If you’re seeing a “Too many open files” error on Nginx, it means that the operating system’s limit on the number of open files has been reached. This can happen when Nginx is running a high-traffic website, serving a large number of requests, and opening a large number of files. Here are some possible solutions … Read more

A manpage is a documentation file that provides detailed information about a specific command, program or function on a Linux/UNIX system. Here are the steps to create a manpage: Choose a name for your manpage: Typically, the name of the manpage should be the same as the name of the command or program you want … Read more

To install or append an SSH key to the authorized_keys file on a remote Linux/Unix server, you can use the ssh-copy-id command. Here are the steps to do so: Open a terminal window on your local machine. Generate an SSH key pair (if you haven’t already): Use the following command to generate a new SSH … Read more

To allow SSH console login but disallow GUI login for a user on Linux, you can modify the user’s login shell to be a non-GUI shell. Here are the steps to do so: Open a terminal window and log in as the root user or another user with administrative privileges. Edit the user’s login shell: … Read more

dhcpdump is a command-line utility that can be used to monitor DHCP (Dynamic Host Configuration Protocol) traffic on a network interface. It is useful for debugging DHCP-related issues, such as when a client is not able to obtain an IP address or when a DHCP server is not responding. Here are the steps to use … Read more