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Timed Access Control
timed (time daemon) is an operating system program that maintains the system time in synchronization with time servers using the Time Synchronization Protocol (TSP) developed by Riccardo Gusella and Stefano Zatti. Gusella and Zatti had done earlier related work on their TEMPO algorithm. The Time Synchronization Protocol specification refers to an election algorithm and a synchronization mechanism specified in other technical reports listed as "to appear". With the release of macOS High Sierra in 2017, timed in macOS has subsumed all time synchronization responsibilities including those of the former ntpd and timed. See also * Network Time Protocol (NTP) * Precision Time Protocol The Precision Time Protocol (PTP) is a protocol for clock synchronization throughout a computer network with relatively high precision and therefore ''potentially'' high accuracy. In a local area network (LAN), accuracy can be sub-microsecon ... (IEEE 1588 PTP) References External links ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MacOS
macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. Within the market of Desktop computer, desktop and laptop computers, it is the Usage share of operating systems#Desktop and laptop computers, second most widely used desktop OS, after Microsoft Windows and ahead of all Linux distributions, including ChromeOS and SteamOS. , the most recent release of macOS is MacOS Sequoia, macOS 15 Sequoia, the 21st major version of macOS. Mac OS X succeeded classic Mac OS, the primary Mac operating systems, Macintosh operating system from 1984 to 2001. Its underlying architecture came from NeXT's NeXTSTEP, as a result of NeXT#1997–2006: Acquisition by Apple, Apple's acquisition of NeXT, which also brought Steve Jobs back to Apple. The first desktop version, Mac OS X 10.0, was released on March 24, 2001. Mac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FreeBSD
FreeBSD is a free-software Unix-like operating system descended from the Berkeley Software Distribution (BSD). The first version was released in 1993 developed from 386BSD, one of the first fully functional and free Unix clones on affordable home-class hardware, and has since continuously been the most commonly used BSD-derived operating system. FreeBSD maintains a complete system, delivering a kernel, device drivers, userland utilities, and documentation, as opposed to Linux only delivering a kernel and drivers, and relying on third-parties such as GNU for system software. The FreeBSD source code is generally released under a permissive BSD license, as opposed to the copyleft GPL used by Linux. The project includes a security team overseeing all software shipped in the base distribution. Third-party applications may be installed using the pkg package management system or from source via FreeBSD Ports. The project is supported and promoted by the FreeBSD Foundation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daemon (computing)
In computing, a daemon is a program that runs as a background process, rather than being under the direct control of an interactive user. Customary convention is to name a daemon process with the letter ''d'' as a suffix to indicate that it's a daemon. For example, is a daemon that implements system logging facility, and is a daemon that serves incoming SSH connections. Even though the concept can apply to many computing systems, the term ''daemon'' is used almost exclusively in the context of Unix-based systems. In other contexts, different terms are used for the same concept. Systems often start daemons at boot time that will respond to network requests, hardware activity, or other programs by performing some task. Daemons such as cron may also perform defined tasks at scheduled times. Terminology In the context of computing, the word is generally pronounced either as or . The term was coined by the programmers at MIT's Project MAC. According to Fernando J. Cor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
System Time
In computer science and computer programming, system time represents a computer system's notion of the passage of time. In this sense, ''time'' also includes the passing of calendar date, days on the calendar. System time is measured by a ''system clock'', which is typically implemented as a simple count of the number of ''ticks'' that have transpired since some arbitrary starting date, called the ''epoch (computing), epoch''. For example, Unix and POSIX-compliant systems encode system time ("Unix time") as the number of seconds elapsed since the start of the Unix epoch at 1 January 1970 00:00:00 Universal Time, UT, with exceptions for leap seconds. Systems that implement the 32-bit and 64-bit versions of the Windows API, such as Windows 9x and Windows NT, provide the system time as both , represented as a year/month/day/hour/minute/second/milliseconds value, and , represented as a count of the number of 100-nanosecond ticks since 1 January 1601 00:00:00 UT as reckoned in the pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of California, Berkeley
The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California), is a Public university, public Land-grant university, land-grant research university in Berkeley, California, United States. Founded in 1868 and named after the Anglo-Irish philosopher George Berkeley, it is the state's first land-grant university and is the founding campus of the University of California system. Berkeley has an enrollment of more than 45,000 students. The university is organized around fifteen schools of study on the same campus, including the UC Berkeley College of Chemistry, College of Chemistry, the UC Berkeley College of Engineering, College of Engineering, UC Berkeley College of Letters and Science, College of Letters and Science, and the Haas School of Business. It is Carnegie Classification of Institutions of Higher Education, classified among "R1: Doctoral Universities – Very high research activity". Lawrence Berkeley National Laboratory was originally founded as par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MacOS High Sierra
macOS High Sierra (version 10.13) is the fourteenth major release of macOS, Apple Inc.'s desktop operating system for Macintosh computers. macOS High Sierra was announced at the WWDC 2017 on June 5, 2017 and was released on September 25, 2017. The name "High Sierra" refers to the High Sierra region in California. Its name signified its goal to be a refinement of the previous macOS version, macOS Sierra, focused on performance improvements and technical updates rather than features. This makes it similar to previous macOS releases Snow Leopard, Mountain Lion and El Capitan. Among the apps with notable changes are Photos and Safari. macOS High Sierra is the final version of macOS to support the Unibody iMac and the Polycarbonate Unibody MacBook, as its successor, macOS Mojave, drops support for the late 2009 and final models. System requirements All Macs that supported macOS Sierra support macOS High Sierra. *iMac (Late 2009 or later) * MacBook (Late 2009 or later) *MacBo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ntpd
The Network Time Protocol daemon (ntpd) is an operating system program that maintains the system time in synchronization with time servers using the Network Time Protocol (NTP). Description The ntpd program is an operating-system daemon that sets and maintains a computer system's system time in synchronization with Internet-standard time servers. It is a complete implementation of the Network Time Protocol (NTP) version 4, but retains compatibility with versions 1, 2, and 3 as defined by RFC 1059, RFC 1119, and RFC 1305, respectively. ntpd performs most computations in 64-bit floating point arithmetic and uses 64-bit fixed point operations only when necessary to preserve the ultimate precision, about 232 picoseconds. While ordinary workstations and networks cannot achieve the ultimate precision , future processors and networks may require it. xntpd is the Network Time Protocol version three (1992) daemon software. The "x" was added to the name because the branch of code that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Time Protocol
The Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-Network latency, latency data networks. In operation since before 1985, NTP is one of the oldest Internet protocols in current use. NTP was designed by David L. Mills of the University of Delaware. NTP is intended to synchronize participating computers to within a few milliseconds of Coordinated Universal Time (UTC). It uses the intersection algorithm, a modified version of Marzullo's algorithm, to select accurate time servers and is designed to mitigate the effects of variable network latency. NTP can usually maintain time to within tens of milliseconds over the public Internet, and can achieve better than one millisecond accuracy in local area networks under ideal conditions. Asymmetric Routing, routes and network congestion can cause errors of 100 ms or more. The protocol is usually described in terms of a client–server model, bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precision Time Protocol
The Precision Time Protocol (PTP) is a protocol for clock synchronization throughout a computer network with relatively high precision and therefore ''potentially'' high accuracy. In a local area network (LAN), accuracy can be sub-microsecond making it suitable for measurement and control systems. PTP is used to synchronize financial transactions, mobile phone tower transmissions, sub-sea acoustic arrays, and networks that require precise timing but lack access to satellite navigation signals. The first version of PTP, IEEE 1588-2002, was published in 2002. IEEE 1588-2008, also known as PTP Version 2, is not backward compatible with the 2002 version. IEEE 1588-2019 was published in November 2019 and includes backward-compatible improvements to the 2008 publication. IEEE 1588-2008 includes a ''profile'' concept defining PTP operating parameters and options. Several profiles have been defined for applications including telecommunications, electric power distribution and aud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
