Write output to file. This is the same as specifying file as the second non-option argument to cpp. gcc has a different interpretation of a second non-option argument, so you must use ‘-o’ to specify the output file.
-c
Compile or assemble the source files, but do not link. The linking stage simplyis not done. The ultimate output is in the form of an object file for each source file. By default, the object file name for a source file is made by replacing the suffix ‘.c’, ‘.i’, ‘.s’, etc., with ‘.o’.
Unrecognized input files, not requiring compilation or assembly, are ignored.
-llibrary
-l library
Search the library named library when linking. (The second alternative with the library as a separate argument is only for POSIX compliance and is not recommended.) It makes a difference where in the command you write this option; the linker searches and processes libraries and object files in the order they are specified. Thus, ‘foo.o -lz bar.o’ searches library ‘z’ after file ‘foo.o’ but before
‘bar.o’. If ‘bar.o’ refers to functions in ‘z’, those functions may not be loaded. The linker searches a standard list of directories for the library, which is actually a file named ‘liblibrary.a’. The linker then uses this file as if it had been specified precisely by name.
The directories searched include several standard system directories plus any that you specify with ‘-L’.
Normally the files found this way are library files—archive files whose members are object files. The linker handles an archive file by scanning through it for members which define symbols that have so far been referenced but not defined.
But if the file that is found is an ordinary object file, it is linked in the usual fashion. The only difference between using an ‘-l’ option and specifying a file name is that ‘-l’ surrounds library with ‘lib’ and ‘.a’ and searches several directories.
