Unix time - Representing the number

Unix time, or POSIX time, is a system for describing points in time. It is widely used not only on Unix-like operating systems but in many other computing systems, including the Java programming language. It is an encoding of UTC, and is sufficiently similar to a linear representation of the passage of time that it is frequently mistaken for one. The main complication is the leap seconds of UTC time. Unix time - Definition. There are two layers of encoding that make up Unix time, and they can be usef ...

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• Unix time - Definition
• Unix time - Encoding time as a number
• Unix time - Representing the number
• Unix time - UTC basis
• Unix time - History
• Unix time - 32-bit overflow
• Unix time - time_t parties

Read more here: » Unix time: Encyclopedia - Unix time

There are two layers of encoding that make up Unix time, and they can be usefully separated. The first layer encodes a point in time as a scalar real number, and the second encodes that number as a sequence of bits or in some other manner. Unix time - Encoding time as a number. Modern Unix time is based strictly on UTC. UTC counts time using SI seconds, and breaks up the span of time into days. UTC days are mostly 86400 s long, but are occasionally 86401 s and could be 86399 s long (though the la ...

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Unix time, Unix time - Definition, Unix time - Encoding time as a number, Unix time - Representing the number, Unix time - UTC basis, Unix time - History, Unix time - 32-bit overflow, Unix time - time_t parties

Read more here: » Unix time: Encyclopedia II - Unix time - Definition

Unix enthusiasts have a history of holding time_t parties to celebrate significant values of the Unix time number. These are directly analogous to the new year celebrations that occur at the change of year in many calendars. As the use of Unix time has spread, so has the practice of celebrating its milestones. Usually it is time values that are round numbers in decimal that are celebrated, following the Unix convention of viewing time_t values in decimal. Among some groups round binary numbers are also celebrated, such as +230 which ...

See also:

Unix time, Unix time - Definition, Unix time - Encoding time as a number, Unix time - Representing the number, Unix time - UTC basis, Unix time - History, Unix time - 32-bit overflow, Unix time - time_t parties

Read more here: » Unix time: Encyclopedia II - Unix time - time_t parties

At 03:14:08 UTC on January 19, 2038 (+231), a 32-bit signed integer representation of Unix time will overflow. Systems using a 32-bit signed integer Unix time_t will therefore be unable to represent that time, or any later, and will likely wrap around to 20:45:52 UTC on December 13, 1901, with integer value -231. This is known as the year 2038 problem. Programs which must handle times beyond the overflow date will need to be changed to use a 64-bit time_t, a bignum representation of Unix time, or so ...

See also:

Unix time, Unix time - Definition, Unix time - Encoding time as a number, Unix time - Representing the number, Unix time - UTC basis, Unix time - History, Unix time - 32-bit overflow, Unix time - time_t parties

Read more here: » Unix time: Encyclopedia II - Unix time - 32-bit overflow

The earliest versions of Unix time had a 32-bit integer incrementing at a rate of 60 Hz, which was the rate of the system clock on the hardware of the early Unix systems. The value 60 Hz still appears in some software interfaces as a result. The epoch also differed from the current value. The first edition Unix Programmer's Manual dated November 3, 1971 defines the Unix time as "the time since 00:00:00, Jan. 1, 1971, measured in sixtieths of a second". It also comments that "the chronologically-minded user will note that 232See also:

Unix time, Unix time - Definition, Unix time - Encoding time as a number, Unix time - Representing the number, Unix time - UTC basis, Unix time - History, Unix time - 32-bit overflow, Unix time - time_t parties

Read more here: » Unix time: Encyclopedia II - Unix time - History