Error while loading shared libraries: libpq.so.7: cannot open shared object file: No such file or di

This error occurs when the system is unable to find the shared library file "libpq.so.7" required by the program. It usually happens when the library is missing or not properly installed.

To resolve this issue, you can try the following steps:

1. Update the package manager: Run the command `sudo apt-get update` (for Ubuntu/Debian-based systems) or `sudo yum update` (for CentOS/RHEL-based systems) to update the package manager.

2. Install the PostgreSQL client library: Run the command `sudo apt-get install libpq-dev` (for Ubuntu/Debian-based systems) or `sudo yum install postgresql-devel` (for CentOS/RHEL-based systems) to install the PostgreSQL client library.

3. Verify the library path: Ensure that the library path is set correctly. You can check it by running the command `echo $LD_LIBRARY_PATH`. If it is empty or does not include the directory containing "libpq.so.7", you may need to add it manually.

For example, if the library is located in "/usr/local/lib", you can add it to the library path by running:

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

You can also add this line to your shell profile file (e.g., ~/.bashrc or ~/.bash_profile) to make it persist across sessions.

4. Rebuild/reinstall the program: If you are building the program from source, ensure that the library is included in the build configuration and rebuild it. If you are using a pre-compiled binary, try reinstalling it to ensure all dependencies are correctly resolved.

By following these steps, you should be able to resolve the "libpq.so.7" shared library error.