Use gcc -v to see what commands it runs. As in,
gcc -v -o hello hello.c
This will print a lot of output, including the linker command. The actual output depends on the platform, but the linking command should be near the end. Alternatively, use
gcc -### -o hello hello.c
This is like -v, but does not actually run any commands and quotes the options.
Another option is
gcc -dumpspecs
Look for the entry for link.
The above command line flags are listed in gcc --help and explained on the man page. Here’s GCC documentation for the spec files.