GCC normal commands

• -c
  Compile and output relocatable object file xxx.o

• -static
  The -static argument tells the compiler driver(calm: gcc) that the linker should build a fully linked executable object file that can be loaded into memory and run without any further linking at load time.

• -L. -lvector
  The -lvector argument is a shorthand for libvector.a,
  The -L. argument tells the linker to look for libvector.a in the current directory.

• -Wall
  Output the details of gcc building process.

• -Werror
  Turns all warnings into erros.

• -fno-common
  Triggers an error if it encounters multiply-defined global symbols.

calmXia: It is recommended and good for you to use -Werror and -fno-common options in your building scripts(ex: makefile), these can help programmer to avoid some subtle and nasty bugs associated with duplicate symbol names. Details see Section 7.6.1 in《CSAPP》3e .