rpclockd

rpclockd is a lightweight Unix utility designed to synchronize a system's hardware clock with an external Network Time Protocol (NTP) server. It is particularly useful in environments where a dedicated NTP daemon like ntpd or chronyd is not required, or where minimal overhead is preferred. The name "rpclockd" is derived from its original purpose of providing a simple replacement for the older rp_time daemon, which was part of the BSD operating system family.

The program operates by periodically querying an NTP server to fetch the current time and adjusting the system clock accordingly. Unlike full-fledged NTP daemons, rpclockd lacks advanced features such as peer selection, time filtering, or detailed logging, making it suitable for basic time synchronization needs. It is often deployed on embedded systems, routers, or servers where resource constraints limit the use of more complex solutions.

rpclockd is typically configured via a configuration file, usually located at `/etc/rpclock.conf`, where users specify the NTP server address, polling interval, and other optional parameters. The daemon runs as a background process, ensuring the system clock remains synchronized without significant computational overhead. It is compatible with most Unix-like systems, including BSD variants and Linux distributions that support the BSD-compatible NTP stack.

While rpclockd is not actively maintained in modern distributions, it remains available in some legacy systems and can be compiled from source if needed. For most contemporary use cases, alternatives like chronyd or ntpd are recommended due to their robustness and additional features. However, its simplicity and minimal resource usage make it a viable option for specific scenarios where a lightweight solution is preferred.