Contents
Shared libraries in Linux are referred as shared objects (generally with extension *. so). These are similar to DLLs in Windows platform. Even shared object files follow the ELF binary format.
Which is the common file extension used for shared library files?
The basics of using a Shared Library file A file with the . SO file extension is a Shared Library file. They contain information that can be used by one or more programs to offload resources so that the application(s) calling the SO file doesn’t have to actually provide the file.
Where are shared libraries stored?
By default, libraries are located in /usr/local/lib, /usr/local/lib64, /usr/lib and /usr/lib64; system startup libraries are in /lib and /lib64. Programmers can, however, install libraries in custom locations. The library path can be defined in /etc/ld.
Shared libraries are libraries that are linked dynamically. Shared libraries allow common OS code to be bundled into a wrapper and used by any application software on the system without loading multiple copies into memory. All the applications on the system can use it without using more memory.
Why do we use shared libraries?
The most significant advantage of shared libraries is that there is only one copy of code loaded in memory, no matter how many processes are using the library. For static libraries each process gets its own copy of the code. This can lead to significant memory wastage.
What is the difference between a shared library and a static library?
Shared libraries are added during linking process when executable file and libraries are added to the memory. Static libraries are much bigger in size, because external programs are built in the executable file. It is faster because shared library code is already in the memory.
There is more than one way in which multiple shared libraries may be added to the linkage of a program, if you are building all the libraries, and the program, yourself.
How to show all shared libraries used by executables in Linux?
Use ldd to list shared libraries for each executable. Change “/bin” above to “/” to search all directories. You’d have to write a little shell script to get to your system-wide breakdown. To find out what libraries a particular executable depends on, you can use ldd command.
How to check shared library dependencies of an executable?
Check shared library dependencies of a program executable. To find out what libraries a particular executable depends on, you can use ldd command. This command invokes dynamic linker to find out library dependencies of an executable. > $ ldd /path/to/program.
To list the required shared libraries of a program, we combine it with grep: Let’s list Vim’s shared libraries using the objdump command: If we compare the output above to the output of the ldd command, we’ll see that the ldd command lists many more libraries than the objdump command.