SoftPrayog provides resources tuned to the Free and Open Source Software (FOSS) philosophy. There are articles on software engineering, tutorials and troubleshooting resources on programs of GNU/Linux environments.
The Coordinated Universal Time (UTC) is the universally accepted time standard. Computers around the world use it as the reference time. It is important that our computers have the correct UTC. The Network Time Protocol (NTP) helps us in synchronizing the time of our computers with the UTC maintained by timeservers.
Software systems often need to act based on time. The accuracy and precision of time maintained by a system is important. Alarms, sleep and high resolution timers provide a framework for application programs to carry out time-critical tasks.
As a process executes, it takes up the CPU time which is also called the execution time or the processor time. The
times system call and the clock library function
can be used by the process to find its execution time.
Linux systems maintain a system clock which stores the calendar time. The is stored as seconds passed since January 1, 1970 00:00:00 UTC. Applications can query this system clock with the time and gettimeofday system calls. There are functions to convert the system calendar time to the familiar local time string.
The hardware real time clock tends to lose or gain time every day by a constant amount. This is called the systematic drift. hwclock program helps in calibrating and adjusting the hardware clock.
