What does the 'ssh' command accomplish?

The 'ssh' command is primarily used to establish secure connections to remote machines over the Secure Shell (SSH) protocol. This technology allows users to log into other computers over a network and execute commands securely, providing a way to perform remote administration, file transfers, and other tasks without exposing sensitive data.

Option B specifically highlights the main function of the 'ssh' command: to connect to remote machines securely. It ensures that the data transmitted between the client and server is encrypted, protecting it from eavesdropping and unauthorized access, which is crucial in maintaining the confidentiality and integrity of the communication.

While it's true that SSH encrypts data in transit, which is alluded to in option C, that function is a part of the broader capability of connecting to remote machines, not the sole purpose of the 'ssh' command itself. The other options do not accurately represent the primary purpose of the 'ssh' command, as they refer to backing up files, performing system updates, or encrypting data in transit without mentioning the critical aspect of remote connectivity.