To extract the third field separated by forward slash (/) delimiter in Unix/Linux shell, you can use the following command: echo “field1/field2/field3/field4” | awk -F’/’ ‘{print $3}’ This uses the awk command to split the input string on forward slashes (/) and then prints the third field ($3). The -F option is used to specify … Read more

You can block specific user agents in Nginx by using the if directive in the server block. Here’s an example: server { … if ($http_user_agent ~* (bad-agent1|bad-agent2)) { return 403; } … } This example blocks requests from user agents that contain the string “bad-agent1” or “bad-agent2”. The return statement returns a HTTP status code … Read more

The $0 variable in a bash script refers to the name of the script itself. However, if the script is being sourced (i.e., run with the source command) rather than executed as a standalone script, $0 will not be able to determine its own location. Here’s an example to illustrate this: # script.sh echo “Script … Read more

  To find out NFS clients connected to an NFS server in Linux or Unix, you can use the following command: showmount -e nfs-server-hostname Replace “nfs-server-hostname” with the actual hostname or IP address of the NFS server. The output of this command will show a list of all the NFS clients that are currently connected … Read more

To remove a symbolic link (also known as a symlink) in Apple OS X, you can use the following command: rm /path/to/symlink Replace “/path/to/symlink” with the actual path to the symlink you want to remove. This will remove the symlink itself, not the target it points to. If you want to remove the target, you … Read more

To reboot a Linux system, you can use the following command: sudo reboot This will immediately restart the system. Note that you need to have root privileges to execute this command. If you are logged in as a regular user, you can use sudo to temporarily elevate your privileges.

To start, stop, or restart network services in Unix, you can use the following commands: Start network service: sudo service network-manager start Stop network service: sudo service network-manager stop Restart network service: sudo service network-manager restart Note that the exact command may vary depending on the specific distribution and version of Unix you are using.

You can use the following command to check a user’s password expiration date and time in Linux: chage -l username Replace “username” with the actual username you want to check. The output will include information about the account, including the password expiration date and time. (https://lsu79.org)

To change the password of a specific user account in Linux, follow these steps: Open the terminal or console. Type the following command and press Enter: sudo passwd [username] Replace [username] with the actual username of the account you want to change the password for. Enter your administrative password when prompted. When prompted, enter the … Read more

In Unix or Linux, you can use the grep command to count the number of occurrences of a word in a file. Here’s how: Open a terminal window and navigate to the directory where the file you want to search is located using the cd command. Use the following command to count the number of … Read more