关于Linux动态库的加载路径

时间:2021-08-16 15:59:23

问题

按如下步骤在Ubuntu上编译安装Google Protocol Buffers

$ ./configure 
$ make
$ make check
$ sudo make install

运行

$ protoc --version 

出现找不到动态库的错误

protoc: error while loading shared libraries: libprotobuf.so.7: cannot open shared object file: No such file or directory 

原因

protobuf的默认安装位置是 /usr/local/usr/local/lib 不在Ubuntu系统默认的 LD_LIBRARY_PATH 里。这个问题 protobuf 的README.txt 写得很清楚,怪自己不仔细。

** Hint on install location **

By default, the package will be installed to /usr/local. However,
on many platforms, /usr/local/lib is not part of LD_LIBRARY_PATH.
You can add it, but it may be easier to just install to /usr
instead. To do this, invoke configure as follows:

./configure --prefix=/usr

If you already built the package with a different prefix, make sure
to run "make clean" before building again.

解决

参考文章里面提供了几种方法,这里只使用其中的一种。

方法1:
1. 创建文件 /etc/ld.so.conf.d/libprotobuf.conf 包含内容

/usr/local/lib

2. 运行命令

$ sudo ldconfig 

这时再运行 protoc --version 就可以得到版本号了

$ protoc --version 
libprotoc 2.4.1

方法2:

  1. vim /etc/profile
  2. export LD_LIBRARY_PATH=~/protobuf-2.5.0
  3. source /etc/profile
  4. $ sudo ldconfig

(LD_LIBRARY_PATH的这里,填写的是protobuf文件的位置)