Linux small Knowledge translation-"UTC and jst"

This week explains "UTC and jst".

There is a time difference between the countries on the Earth. However, the Internet is a global network, and the data transmission across borders is frequent. As a result, servers on the internet need a common time.

In fact, most of the servers on the Internet are using "Coordinated Universal Time (Utc:universal coordinated)". It may have been in the school's geography class, and the GMT used in England is famous for being consistent with UTC. Strictly speaking, GMT and UTC are not the same.

UTC is based on the vibrational time of the cesium atom, and GMT is calculated from the time of January 1, 1958 0:0 0 seconds.

However, the rotation time of the earth is not fixed, so the above calculation method will have some deviations between GMT and UTC, for this reason, to increase the number of "leap seconds" to adjust the GMT and UTC direct deviations.

World time is based on UTC. In Japan, the "Japan Standard Time" (JST), which is 9 hours more than UTC, is used. Conversely, jst subtracts 9 hours and gets UTC time.

JST was once based on the time of the meridian of "longitude 135 degrees" passing through the Bingku County Mss. The current JST is based on the atomic clock as the base of UTC, plus 9 hours later.

However, there is little difference between the time determined by the meridian at 135 degrees east longitude and the current approach to JST.

When administering a server, be sure to note whether the time used by the server is jst or UTC or another time zone.

Like the United States, even the same country has different time zones. So you need to pay special attention when interacting with foreign servers.