strace - Very Useful Flags '-o ' - name of a file into which all system call invocations shall be logged. '-p PID' - trace an already active process, with the given PID. When strace is killed (ctrl-C), the process is detached from, and continues running. '-e' - trace only system calls matching the given filter. '-eopen' - trace only invocations of the 'open' system call. '-f' - follow fork mode - if the traced process forks off another process, start also tracing the new process, along with the old process. This operation is recursive to further forks.