how do I link a c file to two executables - c

Question

I have a file called wrapsock.c that has several wrapper functions for the socket.h header file. I have two executables, FTP_client and FTP_server who both need to use the wrapsock.c file. I am having trouble with my makefile to link the wrapsock.c file to both of these programs
Here is my makefile below:
all: ./bin/FTP_client ./bin/FTP_server
bin/FTP_client: main_client.o wrapsock.o
gcc -o bin/FTP_client main_client.o wrapsock.o -lpthread -g
mv main_client.o ./bin
mv wrapsock.o ./bin
bin/FTP_server: main_server.o wrapsock.o
gcc -o bin/FTP_server main_server.o wrapsock.o -lpthread -g
mv main_server.o ./bin
mv wrapsock.o ./bin
main_client.o: src/main_client.c
gcc -c src/main_client.c -g
wrapsock.o: src/wrapsock.c src/wrapsock.h
gcc -c src/wrapsock.c -g
main_server.o: src/main_server.c
gcc -c src/main_server.c -g
clean:
rm ./bin/*.o
rm ./bin/FTP_client
rm ./bin/FTP_server
This is the error I am receiving:
gcc -c src/main_client.c -g
gcc -c src/wrapsock.c -g
gcc -o bin/FTP_client main_client.o wrapsock.o -lpthread -g
mv main_client.o ./bin
mv wrapsock.o ./bin
gcc -o bin/FTP_server main_server.o wrapsock.o -lpthread -g
gcc: error: wrapsock.o: No such file or directory
make: *** [makefile:9: bin/FTP_server] Error 1

Answer 1

mv wrapsock.o ./bin
gcc -o bin/FTP_server main_server.o wrapsock.o -lpthread -g
gcc: error: wrapsock.o: No such file or directory
To move the object is not a good way, create the objects directly into the directory bin as you do for the executable :
all: ./bin/FTP_client ./bin/FTP_server
bin/FTP_client: bin/main_client.o bin/wrapsock.o
gcc -o bin/FTP_client bin/main_client.o bin/wrapsock.o -lpthread -g
bin/FTP_server: bin/main_server.o bin/wrapsock.o
gcc -o bin/FTP_server bin/main_server.o bin/wrapsock.o -lpthread -g
bin/main_client.o: src/main_client.c
gcc -c src/main_client.c -g -o bin/main_client.o
bin/wrapsock.o: src/wrapsock.c src/wrapsock.h
gcc -c src/wrapsock.c -g -o bin/wrapsock.o
bin/main_server.o: src/main_server.c
gcc -c src/main_server.c -g -o bin/main_server.o
clean:
rm ./bin/*.o
rm ./bin/FTP_client
rm ./bin/FTP_server

Answer 2

Not sure why are you moving the binary objects to bin/, but after you've built your client target wrapsock.o is no longer in project root and resides in bin/ instead, so when server target gets its turn, gcc can no longer find it. I would just ditch the moves or if there is a reason for performing them, do so in a separate target that is done only after both binaries have been built (i.e. lists them as prerequisites).