Final answer:
Use the 'du' command to see disk space used by each file in a directory. The 'ls -l' and 'ls -la' commands show file sizes but do not provide comprehensive disk usage like 'du'.
Step-by-step explanation:
To find out how much disk space each file in the current directory uses, the command you would use is du, which stands for disk usage. The ls command, with the -l (long format) option, will give you details about the files, such as permissions, number of links, owner, group, file size, and the last modified time. Using ls with the -la option will display all files, including hidden ones, with the same detailed format. While both ls -l and ls -la do show file sizes, they do not sum the sizes of files in directories or provide as comprehensive information about disk space usage as du.