How strace helps debug silent process failures that logs cannot explain

When a daemon fails to start under systemd without producing any log output, the Linux diagnostic tool strace can reveal what is happening at the system-call level before application logging kicks in. In one documented case, strace exposed a process silently dying because it could not resolve an expected path in /var/run/, a problem invisible to standard logs. The tool's -f flag allows it to follow forked child processes, while filters like -e trace=write help narrow down relevant output quickly. A key finding was that the process was writing error output to stderr, which systemd suppresses unless explicitly configured to route it to the journal. While strace introduces overhead and should not be run continuously on high-throughput systems, it serves as a reliable last resort when application-level diagnostics offer nothing.