How to find all the aliases within a given file system?
To find aliases with mdfind, in a Terminal:

mdfind kMDItemKind="Alias"

This will print a list of aliases with the fully qualified pathname.

Note:  These are aliases created in Finder, not symbolic links created with the ln command from a Terminal or script.

To use find to find symbolic links created by, as an example, ln have a look at: man find

Example: find / -type l

This will start in the root of the Macintosh HD and traverse the entire filesystem that you have permission to read and output all symbolic links created by, as an example, ln showing the fully qualified pathname.

To augment the basic command example read man find.