`gcc -o hello hello.c` - Create executable with name hello

`gcc -c hello.c` - Preprocess and compile only

`gcc hello.o -lm` - tells the compiler(ie. gcc) to link the executable file with the given library (math.h here)

`gcc -x c hello.txt` - `-x` option asks for source language

`gcc -std=89 hello.c` - `-std` option is for specifying standard

`gcc -I ./sources -o hello hello.c` - `-I` option is for path to header files

## Creating and using Static libraries

`gcc -c greet.c` - Create `greet.o` after compiling greet.c

`ar cr libgreet.a greet.o` - Create static library (archive) from object file

`ar -tvf libgreet.o` - See the contents of an archive file

`gcc -L ./ -o hello hello.c -lm -lgreet` - `-L` option specifies the directory to search the static library

### Creating and using Dynamic libraries

`gcc -c -fPIC greet.c` - Generate object file in fixed position code format

`gcc hello.o -shared -o libgreet.so` - Create dynamic library (.so) from object file

`gcc -I ./headers -L ./ -o hello hello.c -lgreet` - Link dynamic library during linking stage

## Other useful flags

`-Wall` - enable *all* the compile time warning messages

`-O<level>` - This option is used to specify the code optimisation level. `<level>` here is an integer. This way while generating binary code for macros, or loop statements, or pointer/string operations, gcc can produce more efficient/faster code.

`-g` - Adds extra information to the executable which can be used for debugging

`-S` - Used to produce the compilation output in an assembly language, i.e. a step just before the code generation. It produces a `.s` file while contains program in assembly code.