while patching oracle 12c database on Linux OS environment, i faced the below error while applying the patch using Opatch utility (although the database is shutdown):

Verifying environment and performing prerequisite checks…

Prerequisite check “CheckActiveFilesAndExecutables” failed.

The details are:

Following executables are active :

/oracl/db11/product/12.1.0.2/lib/libclntsh.so.12.1

UtilSession failed: Prerequisite check “CheckActiveFilesAndExecutables” failed.

solution:

find the process that is locking the file system using the fuser command

fuser -u /oracl/db11/product/12.1.0.2/lib/libclntsh.so.12.1

and then kill it using kill -9 command