list directory contents
syntax: ls [flags] [<director(y/ies)/file(s)>]

ls will list the contents of a directory. ls by itself will list
the current directory. You can specify a list of a directories and/or
files to list as well as several flags to control how the display
appears. Wild cards can be used. Common wild cards are:
* - match anything 0 or more characters long
? - match one character
[x-y] - match any 1 character between x and y (i.e. [a-z]
[abc] - match abs (i.e. [agh]) (can be longed then 3
i.e. [abdteh])
[combination of above] - i.e. [adeA-Zhu-z]
Common Flags:
-a - list all files including ., .. and all those beginning
with a '.' (Files beginning with a . are normally not
shown).
-s - show size of files
-l - show owner, permissions, size, group, etc.. of file
-C - show in columns
-F - append * to executables, / to directories, @ for links,
etc.
-t - sort in reverse order by time.