#ld_library_path

Bibliotecas Compartilhadas no Linux

Aprenda como funcionam as biblitoecas compartilhadas (shared libraries) no Linux, e como isso pode interferir no funcionamento dos programas.

Determinar quais as bibliotecas compartilhadas de que um programa executável depende para executar e instalá-las quando necessário faz parte dos objetivos do exame.

Para entendermos a gerência das bibliotecas compartilhadas, precisamos primeiro…

Fix all your “cannot open shared object file” problems in Linux

After installing Oracle XE on Linux, and especially Ubuntu, you might find yourself with issues opening SQL*Plus and other tools.

“sqlplus: error while loading shared libraries: libclntsh.so.11.1: cannot open shared object file: No such file or directory”

There are many possible reasons for that, so check the following:

Set your paths correctly

Perform the commands:

oracle@VirtualBox:~$ echo…

引自：设置 Linux 的 LD_LIBRARY_PATH 变量

在 Linux 下，如果你写好了自己的动态链接库，需要在其它程序里调用，则需要让这些程序能找到这些动态链接库。如果设置不对，会出现类似如下的错误：

test: error while loading shared libraries: libexampleso.so.0: cannot open shared object file: No such file or directory

这是因为没有把动态链接库的安装路径（例如说是 /usr/local/lib ）放到变量 LD_LIBRARY_PATH 里。

这时，可以用命令 export 来临时测试确认是不是这个问题：

export LD_LIBRARY_PATH=/usr/local/lib

在终端里运行上面这行命令，再运行这个可执行文件，如果运行正常就说明是这个问题。

接下来的问题是：以上做法，只是临时设置变量 LD_LIBRARY_PATH ，下次开机，一切设置将不复存在；如何把这个值持续写到 LD_LIBRARY_PATH 里呢？

我们可以在 ~/.bashrc 或者 ~/.bash_profile 中加入 export 语句，前者在每次登陆和每次打开 shell 都读取一次，后者只在登陆时读取一次。我的习惯是加到 ~/.bashrc 中，在该文件的未尾，可采用如下语句来使设置生效：

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib