ubuntu20.04编译so依赖问题

问题

经常会遇到：

/usr/bin/ld: xxxx.so: undefined reference to `libiconv'
/usr/bin/ld: xxxx.so: undefined reference to `libiconv_close'
/usr/bin/ld: xxxx.so: undefined reference to `libiconv_open'

或者：

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

查看：

$ ldd test
        linux-vdso.so.1 (0x00007ffe09f3e000)
        /$LIB/libonion.so => /lib/x86_64-linux-gnu/libonion.so (0x00007fbb415e9000)
        xxxx.so => not found
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fbb413ec000)
        libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fbb413e6000)
        /lib64/ld-linux-x86-64.so.2 (0x00007fbb416f6000)

检查makefile

xxxx.so 工程 makefile 需要添加依赖项 iconv

LIBRARY =  -lm -liconv -L/usr/local/lib

编译安装缺少的库 libiconv

wget http://ftp.gnu.org/pub/gnu/libiconv/libiconv-1.16.tar.gz
tar zxvf libiconv-1.16.tar.gz
cd libiconv-1.16
./configure --prefix=/usr/local
make
make install

自定义so库建立连接

cp xxxx.so /usr/local/lib
ln -s /usr/local/lib/xxxx.so /usr/lib/xxxx.so