In this short video, we will learn how to use the for loop on Linux to generate a block of IP addresses. The for loop needs three parts: the initialization, the condition, and the advancement to the next iteration.
A default class C IP subnet has 256 IP addresses. These addresses have the same value in the first three octets. In the last octet, they have a unique value from the range 0 to 255. The shell will run this loop 256 times and generate a new sequential number on each run. If we use the generated numbers as the last octet of this string, we get all IP addresses of this subnet.
We can also save these IP addresses in a file. We can use the shell's redirection feature to send the output of this command to a file.
If we want these IP addresses in a single line, we can use the paste command. It prints all lines of the specified file in a single line. It uses a comma to separate lines' values.
If we need IP addresses in CSV format, we can redirect the output of the paste command to a new file.