.. (double dot) is a special directory in most operating systems that represents the parent directory of the current directory. It is typically used to move up one level in the directory hierarchy. For example, if you are in the `/home/user/documents` directory, and you want to move up to the `/home/user` directory, you can use the following command: “` cd .. “` This command will move you up one level in the directory hierarchy, to the parent directory of the current directory. .. can also be used in conjunction with other commands to navigate the directory hierarchy. For example, the following command will move you up two levels in the directory hierarchy: “` cd ../.. “` And the following command will move you to the root directory of the file system: “` cd / “` .. is a useful command for navigating the directory hierarchy quickly and easily. It can be used to move up one or more levels in the directory hierarchy, or to move to the root directory of the file system.COVID-19 Vaccine Rollout Accelerates Nationwide As the COVID-19 pandemic continues to impact the world, the rollout of vaccines has become a critical step in controlling the virus. In the United States, the vaccine rollout has accelerated significantly in recent weeks, with millions of doses being administered each day. According to the Centers for Disease Control and Prevention (CDC), as of February 12, 2021, over 37 million Americans have received at least one dose of a COVID-19 vaccine. Of those, over 14 million have received both doses and are fully vaccinated. The vaccine rollout has been made possible through the efforts of manufacturers, healthcare workers, and government agencies. Pfizer and Moderna have been producing and distributing the two mRNA vaccines that have been authorized for use in the United States. Healthcare workers have been administering the vaccines at hospitals, clinics, and vaccination sites across the country. The Biden administration has also played a key role in the vaccine rollout. The administration has set a goal of vaccinating 100 million Americans in its first 100 days in office. To achieve this goal, the administration has increased funding for vaccine production and distribution, and has expanded the availability of vaccination sites. The vaccine rollout has been met with both enthusiasm and skepticism. Many people are eager to get vaccinated and protect themselves from the virus. However, some people have expressed concerns about the safety and efficacy of the vaccines. The CDC has emphasized that the vaccines are safe and effective, and has urged people to get vaccinated as soon as possible. The vaccine rollout is an important step in the fight against COVID-19. As more and more people get vaccinated, the number of cases and deaths from the virus is expected to decline. The vaccine rollout is a symbol of hope that the pandemic will eventually come to an end.