Thus, in this case, the command is ls, it is followed by optional hyphen-letter combinations, then one or more filenames. Now, you can see that ls has many options. A very useful one is the following. It is a short description of how to use the program. There may or may not be other sections, such as the following.
Environment variables are special types of shell variables.
ALSO - Gives the names of related programs. This section can be extremely useful. The SEE ALSO section tells you about other commands related to the current one. This section tells about known bugs in the command. You may wonder why, f they know about bugs, they don't just fix them.