Do not put header.h
in your command line:
cc -c source.c -o a_name_different_than_source.o
will work.
Question
When I intuitively try to run such command
cc -c source.c header.h -o a_name_different_than_source.o
the following error is thrown
cc: cannot specify -o with -c, -S or -E with multiple files
Solution
Do not put header.h
in your command line:
cc -c source.c -o a_name_different_than_source.o
will work.
OTHER TIPS
A .c file does not require you to mention the headers on the command line, GCC takes care of that.
A simple gcc inputFilename -o outfileName
should suffice.