Linux shared libraries

Linux shared Libraries

Shared libraries in Linux are typically named with. so.x.y.z, where x, Y, Z are the main version number, minor version number, and release version number. The same library, the major version number is incompatible with each other, the main version is the same, the minor version number of the cubby minor version number of the library has some updates, add some interface symbols and keep the original interface symbol unchanged, but remain compatible; the major and minor version numbers are the same, the release version number is different, which indicates some modification of the library. No new features are added.

So-name Soft Links

So-name Soft Links: Shared library libname.so.x.y.z So-name soft links are named libname.so.x, which removes the minor version number and the release version number. It points to a library of Libname with the major version number x, which is generally the latest Libname library with the main version number x.
When invoking the dynamic library, the program finds the actual library file through the So-name Soft link of the library and makes the call. After you install or update the library libname.x.y.z in the system, you need to perform ldconfig to create or update the So-name soft link for the Libname library, so that the libname.so.x soft link points to the latest library.

LDD Command

The LDD command is used to see which dynamic libraries are required by the program. The essence is realized through ld-linux.so, the Ld-linux.so module will work before the executable program and gain control. Actually LDD EXE, equivalent to executing/lib/ld-linux.so.2--list exe

ld-linux.so

Ld-linux.so is a library file for dynamic loaders that dynamically link some libraries when the program executes.
When a program is started, ld-linux.so is called, Ld-linux.so detects which dynamic libraries The program relies on, and then searches the system for the presence of the required dynamic library files. The order in which they are searched is:
1. Ld_library_path The specified directory
2. The library path in/etc/ld.so.cache (Ld.so.cache is the/etc/ld.so.conf cache for quick lookups, which is actually equivalent to finding the path specified in the/etc/ld.so.conf configuration file)
4. Default library path/lib,/usr/lib

Linux shared libraries