sudo systemd-resolve --set-dns=8.8.8.8 --interface=<interface name>

Source: networking – DNS issues after upgrading to 20.04 – Ask Ubuntu

int is_valid_fd(int fd)
{
    return fcntl(fd, F_GETFL) != -1 || errno != EBADF;
}

Source: c – How to check if a given file descriptor stored in a variable is still valid? – Stack Overflow

Source: Storing Data in Node-Red Variables

You can disable it by adding --column-statistics=0. The command will be something like:

mysqldump --column-statistics=0 --host=<server> --user=<user> --password=<password>

Source: mysql – mysqldump throws: Unknown table ‘COLUMN_STATISTICS’ in information_schema (1109) – Server Fault