What command do you use to list all files in a directory?

The command used to list all files in a directory is "ls -a." This command is specifically designed to show all files, including hidden files, which are those that begin with a dot (.) in their name. By using the '-a' option with the 'ls' command, you instruct the system to include these hidden files in the output.

The basic 'ls' command by itself lists only the visible files and directories in the current directory. The command 'dir' may also be used on some Linux systems to display directory contents, but it does not provide the same functionality in terms of showing hidden files by default. The option 'list' does not correspond to any command in the Linux command line for listing files, making it incorrect. Therefore, "ls -a" is the most appropriate command for ensuring that all files, including hidden ones, are shown in the directory listing.