gcc -l links with a library file.
gcc -L looks in directory for library files.
$ gcc [options] [source files] [object files] [-Ldir] -llibname [-o outfile]
Link -l with library name without the lib prefix and the .a or .so extensions.
For static library file libmath.a use -lmath:
$ gcc -static myfile.c -lmath -o myfile
For shared library file libmath.so use -lmath:
$ gcc myfile.c -lmath -o myfile
file1.c:
// file1.c
#include <stdio.h>
void main()
{
printf("main() run!\n");
myfunc();
}
file2.c:
// file2.c
#include <stdio.h>
void myfunc()
{
printf("myfunc() run!\n");
}
Build file2.c, copy object file file2.o to libs directory and archive it to static library libmylib.a:
$ gcc -c file2.c
$ mkdir libs
$ cp file2.o libs
$ cd libs
$ ar rcs libmylib.a file2.o
Build file1.c with static library libmylib.a in libs directory.
Build without -L results with an error:
$ gcc file1.c -lmylib -o outfile
/usr/bin/ld: cannot find -llibs
collect2: ld returned 1 exit status
$
Build with -L and run:
$ gcc file1.c -Llibs -lmylib -o outfile
$ ./outfile
main() run!
myfunc() run!
$