The {$LINKLIB name} will link to a library name. This has the effect of passing -lname to the linker.
As an example, consider the following unit:
unit getlen;
interface
{$LINKLIB c}
function strlen (P : pchar) : longint;cdecl;
implementation
function strlen (P : pchar) : longint;cdecl;external;
end.
If one would issue the command
ppc386 foo.pp
where foo.pp has the above unit in its uses clause, then the compiler would link the program to the c library, by passing the linker the -lc option.
The same can be obtained by removing the linklib directive in the above unit, and specify -k-lc on the command line:
ppc386 -k-lc foo.pp
Note that the linker will look for the library in the linker library search path: one should never specify a complete path to the library. The linker library search path can be set with the -Fl command line option.