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IPv6 multicast interface selection

The setsockopt way to select an interface for the outgoing traffic with IPv4 is IP_MULTICAST_IF, which accepts two arguments. From the ip(4) manual page: Set the local device for a multicast socket. The argument for setsockopt(2) is an ip_mreqn or (since Linux 3.5) ip_mreq structure similar to IP_ADD_MEMBERSH…

Echo only valid user

Bash newbie question: I’d like to have this script echo out only users from a given list that are valid user IDs, and not echo the invalid ones. Here’s what I have so far: Instead, it is echoing out the results of ‘id’ as well as the text “is not valid user ID” Ideally, it&…

grep command in linux using ” in regex

I have the following linux cmd: The text i have is the following: Of course the output i want to have is: Why dont i have the correct output? Because of the ” required by the grep which mix with ” in my text? How to fix it? Answer You could use the following regex: Original poster provided a regex

fopen() returns inavlid argument when writing on SD card?

I’m trying to write a file on SD card if it’s inserted into the kit. Otherwise, the file should be written to the current directory of the project. I can write the file in the project’s directory without any problems. However, when I try to write it on the inserted SD card, it returns Invali…