What Is Ld_library_path Linux


Have you ever encountered a situation where you tried to run a program or execute a command on your Linux system, only to be met with an error message stating that a certain library or file could not be found? If so, you may have come across the concept of LD_LIBRARY_PATH in Linux.

In simple terms, LD_LIBRARY_PATH is an environment variable that tells the system where to look for shared libraries at runtime. When a program is executed, it may rely on various libraries to function correctly. These libraries contain precompiled code that can be reused by multiple programs, reducing redundancy and improving performance. However, if the system cannot find the required library, the program will fail to run.

In such cases, the LD_LIBRARY_PATH variable can come to the rescue. By setting this variable, you can specify additional directories to be searched for shared libraries. When the program is launched, the system will look for the required libraries in the directories specified by the LD_LIBRARY_PATH variable, in addition to the default directories.

It’s important to note that the directories specified by LD_LIBRARY_PATH are searched in the order they are listed. This means that if multiple directories contain libraries with the same name, the system will prioritize the one in the directory listed first in LD_LIBRARY_PATH.

Here’s an example to help illustrate how LD_LIBRARY_PATH works:

export LD_LIBRARY_PATH=/path/to/dir1:/path/to/dir2

  1. The export keyword is used to create or modify an environment variable.
  2. /path/to/dir1: specifies the first directory to be searched.
  3. /path/to/dir2 specifies the second directory to be searched.

By executing the above command, any program launched afterwards will search for shared libraries in /path/to/dir1 and /path/to/dir2 in addition to the default directories.

It’s worth mentioning that the LD_LIBRARY_PATH variable is not persistent. This means that it only affects the current session and will be reset once you close the terminal. If you want to make the change permanent, you can add the export command to your shell configuration file, like .bashrc or .bash_profile.

In conclusion, the LD_LIBRARY_PATH environment variable plays a crucial role in Linux systems when dealing with shared libraries. By properly setting this variable, you can ensure that your programs have access to the required libraries, preventing errors and enabling smooth execution. So, the next time you encounter a library-related error, remember to check your LD_LIBRARY_PATH!