Which command can be used to see a summary or listing of files in Linux?

The command used to see a summary or listing of files in Linux is "ls." This command stands for "list" and it displays a directory's contents, providing a view of files and folders contained within it. By default, when you enter the "ls" command in the terminal, it lists the files in the current working directory without showing hidden files. You can also enhance the output with various options, such as using the "-l" flag to provide a detailed view that includes file permissions, owners, sizes, and modification dates.

The other options serve different purposes: "paste" is used to merge lines of files; "updatedb" updates the database used by the locate command for file searching, and "tr" is a utility for translating or deleting characters from standard input. Each of these commands has its own specific functionality that does not involve listing files directly in a directory.