strace

strace is a Linux diagnostic tool that traces and logs the system calls a running program makes to the operating system kernel, such as opening files, reading input, or allocating memory. It helps diagnose problems related to file access, permissions, or unexpected system-level behavior without needing to modify or recompile the program being examined. Because it operates at the system call level, it is especially useful for debugging issues outside the program's own source code, like missing files or failed permissions.