A Beginner’s Guide to Using gcc: Compilation Process, Static and Dynamic Library Creation

As a Java developer who often forgets the basic usage of gcc , the author writes a concise tutorial to record the essential steps of compiling C programs and building static and dynamic libraries.

Compilation Process

Step 1: Preprocess – expands header files, replaces macro definitions, and removes false conditional compilation blocks. Command:

gcc -E hello.c -o hello.i

Step 2: Compile – translates the preprocessed source into assembly language. Command:

gcc -S hello.i -o hello.s

Step 3: Assemble – converts the assembly file into an ELF relocatable object file. Command:

gcc -c hello.s -o hello.o

Step 4: Link – links the object file to produce an executable, either dynamically or statically.

# Dynamic linking
gcc hello.o -o hello
# Static linking
gcc hello.o -o hello -static

Static Library Creation

Write a simple addition function in add.c :

#include
int add(int a, int b) {
    return a + b;
}

Compile it to an object file:

gcc -c add.c -o add.o

Create a static library:

ar rcs libadd.a add.o

Write a test program that calls add , compile and link with the static library:

gcc test.c -o test libadd.a

Running ./test prints the result 3 .

Dynamic Library Creation

Compile the source with position‑independent code:

gcc -c add.c -o add.o -fPIC

Build a shared library:

gcc -shared -o libadd.so add.o

Alternatively, a one‑step command:

gcc -fPIC -shared -o libadd.so add.c

Write the same test program, compile and link against the shared library:

gcc test.c -o test -ladd -L ./

Running the executable initially fails because the dynamic loader cannot find libadd.so :

./test
error while loading shared libraries: libadd.so: cannot open shared object file: No such file or directory

Copy the library to a standard search path (e.g., /lib64 ) and run again:

cp libadd.so /lib64
./test
3

Verify the linkage with ldd :

ldd test
    linux-vdso.so.1 =>  (0x00007ffe0f597000)
    libadd.so => /lib64/libadd.so (0x00007fa5ab29f000)
    libc.so.6 => /lib64/libc.so.6 (0x00007fa5aaed1000)
    /lib64/ld-linux-x86-64.so.2 (0x00007fa5ab4a1000)

In summary, the article walks through the complete gcc workflow, from source code to executable, and shows how to package code into static and shared libraries, providing essential commands and example code for each step.