C static libraries

ubuntu@ip-172-31-63-244:~/julien$ l total 44 drwxrwxr-x 2 ubuntu ubuntu 4096 Mar 25 02:47 . drwxrwxr-x 19 ubuntu ubuntu 4096 Mar 25 02:44 .. -rw-rw-r-- 1 ubuntu ubuntu 89 Mar 25 02:44 0-print_z.c -rw-rw-r-- 1 ubuntu ubuntu 132 Mar 25 02:44 1-print_alphabet.c -rw-rw-r-- 1 ubuntu ubuntu 132 Mar 25 02:44 2-print_tebahpla.c -rw-rw-r-- 1 ubuntu ubuntu 166 Mar 25 02:44 3-print_base16.c -rw-rw-r-- 1 ubuntu ubuntu 162 Mar 25 02:44 4-positive_or_not.c -rw-rw-r-- 1 ubuntu ubuntu 636 Mar 25 02:44 5-print_number.c -rw-rw-r-- 1 ubuntu ubuntu 178 Mar 25 02:47 my_functions.h -rw-rw-r-- 1 ubuntu ubuntu 76 Mar 25 02:44 print_char.c -rw-rw-r-- 1 ubuntu ubuntu 1392 Mar 25 02:46 print_char.o ubuntu@ip-172-31-63-244:~/julien$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 -c *.c ubuntu@ip-172-31-63-244:~/julien$ l total 68 drwxrwxr-x 2 ubuntu ubuntu 4096 Mar 25 02:47 . drwxrwxr-x 19 ubuntu ubuntu 4096 Mar 25 02:44 .. -rw-rw-r-- 1 ubuntu ubuntu 89 Mar 25 02:44 0-print_z.c -rw-rw-r-- 1 ubuntu ubuntu 1400 Mar 25 02:47 0-print_z.o -rw-rw-r-- 1 ubuntu ubuntu 132 Mar 25 02:44 1-print_alphabet.c -rw-rw-r-- 1 ubuntu ubuntu 1408 Mar 25 02:47 1-print_alphabet.o -rw-rw-r-- 1 ubuntu ubuntu 132 Mar 25 02:44 2-print_tebahpla.c -rw-rw-r-- 1 ubuntu ubuntu 1408 Mar 25 02:47 2-print_tebahpla.o -rw-rw-r-- 1 ubuntu ubuntu 166 Mar 25 02:44 3-print_base16.c -rw-rw-r-- 1 ubuntu ubuntu 1464 Mar 25 02:47 3-print_base16.o -rw-rw-r-- 1 ubuntu ubuntu 162 Mar 25 02:44 4-positive_or_not.c -rw-rw-r-- 1 ubuntu ubuntu 1472 Mar 25 02:47 4-positive_or_not.o -rw-rw-r-- 1 ubuntu ubuntu 636 Mar 25 02:44 5-print_number.c -rw-rw-r-- 1 ubuntu ubuntu 2048 Mar 25 02:47 5-print_number.o -rw-rw-r-- 1 ubuntu ubuntu 178 Mar 25 02:47 my_functions.h -rw-rw-r-- 1 ubuntu ubuntu 76 Mar 25 02:44 print_char.c -rw-rw-r-- 1 ubuntu ubuntu 1392 Mar 25 02:47 print_char.o ubuntu@ip-172-31-63-244:~/julien$ ar -rc libschool.a *.o ubuntu@ip-172-31-63-244:~/julien$ ar -t libschool.a 0-print_z.o 1-print_alphabet.o 2-print_tebahpla.o 3-print_base16.o 4-positive_or_not.o 5-print_number.o print_char.o ubuntu@ip-172-31-63-244:~/julien$ ranlib libschool.a ubuntu@ip-172-31-63-244:~/julien$ cat main.c void print_alphabet(void); int main(void) { print_alphabet(); return (0); } ubuntu@ip-172-31-63-244:~/julien$ gcc main.c /tmp/ccQa2r6L.o: In function `main': main.c:(.text+0x5): undefined reference to `print_alphabet' collect2: error: ld returned 1 exit status ubuntu@ip-172-31-63-244:~/julien$ gcc main.c -L. -lschool -o alpha ubuntu@ip-172-31-63-244:~/julien$ ./alpha abcdefghijklmnopqrstuvwxyzubuntu ubuntu@ip-172-31-63-244:~/julien$