ncat:tldr:50fee

The command ncat -l ${port} > ${filename} is a command-line instruction which will start the ncat program, listen on a specified port, and redirect the incoming data to a file with the given filename.

Here's a breakdown of the different components in the command:

• ncat: It is a command-line utility that serves as a powerful networking tool. It can listen, redirect, or establish connections over various protocols.
• -l: The -l option instructs ncat to listen on a specific port for incoming connections.
• ${port}: This should be replaced with the actual port number where ncat will listen for incoming connections. For example, if ${port} is set to 8080, ncat will listen on port 8080.
• >: This symbol is known as output redirection. It instructs the shell to redirect standard output to a file instead of displaying it on the terminal.
• ${filename}: This should be replaced with the desired filename where the incoming data from ncat will be saved. For example, if ${filename} is set to output.txt, the received data will be stored in the output.txt file.

Combining all the elements together, the command ncat -l ${port} > ${filename} launches ncat to listen on the specified ${port} (e.g., port 8080) and saves the incoming data to a file named ${filename} (e.g., output.txt), which will be created or overwritten in the process.