简单的 libnotify "hello world" 程序无法在 Ubuntu 20.04 上编译并出现链接器错误

Question

我可能在这里遗漏了一些非常基本的东西，但由于某种原因，我无法在我的 Ubuntu 20.04 系统上成功地 link 对抗 libnotify，即使一切都已正确安装并且 pkg- cfg（恕我直言）returns 正确的选择...有什么想法吗？

user@home:~/jabrac$ ldconfig -v | grep notify                                                                                                                                                                                                                                                                      
        libnotify.so.4 -> libnotify.so.4.0.0

user@home:~/jabrac$ dpkg -L libnotify-dev 
/.
/usr
/usr/include
/usr/include/libnotify
/usr/include/libnotify/notification.h
/usr/include/libnotify/notify-enum-types.h
/usr/include/libnotify/notify-features.h
/usr/include/libnotify/notify.h
/usr/lib
/usr/lib/x86_64-linux-gnu
/usr/lib/x86_64-linux-gnu/pkgconfig
/usr/lib/x86_64-linux-gnu/pkgconfig/libnotify.pc
/usr/share
/usr/share/doc
/usr/share/doc/libnotify-dev
/usr/share/doc/libnotify-dev/copyright
/usr/share/gir-1.0
/usr/share/gir-1.0/Notify-0.7.gir
/usr/lib/x86_64-linux-gnu/libnotify.so
/usr/share/doc/libnotify-dev/changelog.Debian.gz
user@home:~/jabrac$ ls -l /usr/lib/x86_64-linux-gnu/libnotify.so*
lrwxrwxrwx 1 root root    14 Mär 20  2020 /usr/lib/x86_64-linux-gnu/libnotify.so -> libnotify.so.4
lrwxrwxrwx 1 root root    18 Mär 20  2020 /usr/lib/x86_64-linux-gnu/libnotify.so.4 -> libnotify.so.4.0.0
-rw-r--r-- 1 root root 38984 Mär 20  2020 /usr/lib/x86_64-linux-gnu/libnotify.so.4.0.0

user@home:~/jabrac$ cat hello_world.c 
#include <libnotify/notify.h>
#include <stdio.h>

int main(int argc, char * argv[] ) 
{
    notify_init("Sample");
    NotifyNotification* n = notify_notification_new ("Hello world", 
                                 "some message text... bla bla",
                                  0);
    notify_notification_set_timeout(n, 10000); // 10 seconds

    if (!notify_notification_show(n, 0)) 
    {
        printf("show has failed\n");
        return -1;
    }
    return 0;
}
user@home:~/jabrac$ gcc `pkg-config --cflags --libs libnotify` hello_world.c 
/usr/bin/ld: /tmp/cckbaX1n.o: in function `main':
hello_world.c:(.text+0x1b): undefined reference to `notify_init'
/usr/bin/ld: hello_world.c:(.text+0x33): undefined reference to `notify_notification_new'
/usr/bin/ld: hello_world.c:(.text+0x48): undefined reference to `notify_notification_set_timeout'
/usr/bin/ld: hello_world.c:(.text+0x59): undefined reference to `notify_notification_show'
collect2: error: ld returned 1 exit status

user@home:~/jabrac$ pkg-config --cflags --libs libnotify
-pthread -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/libmount -I/usr/include/blkid -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -lnotify -lgdk_pixbuf-2.0 -lgio-2.0 -lgobject-2.0 -lglib-2.0

Answer 1

正如@Someprogrammerdude 上面所说，您需要在程序后指定-l 选项。这是 gcc(1) 手册页中的相关部分：

-llibrary
...
It makes a difference where in the command you write this option; the linker searches and processes libraries and object files in the order they are specified. Thus, foo.o -lz bar.o searches library z after file foo.o but before bar.o. If bar.o refers to functions in z, those functions may not be loaded.

简单的 libnotify "hello world" 程序无法在 Ubuntu 20.04 上编译并出现链接器错误

Simple libnotify "hello world" program fails to compile on Ubuntu 20.04 with linker error

c

ubuntu

libnotify