How do I find a particular file in the environment

Use the Linux command "find"

Let us say that you've installed a library via the postInstall script, and now you want to find a file name ending in the extension .so. Run a command like find / -name *.so. This will look through all files -- starting in the / directory, which is root -- for files with the characters .so in their filenames. (The * is a wildcard, instructing the computer to look for all possible combinations of things ending in .so .) Here is a lifewire article explaining the 'find' command in more detail. You can do this from either a shell script or an interactive terminal session.