Editing Unix time (section)

== Usage ==
Unix time is widely adopted in computing beyond its original application as the system time for [[Unix]]. Unix time is available in almost all system programming [[API]]s, including those provided by both Unix-based and non-Unix [[operating systems]]. Almost all modern [[programming languages]] provide APIs for working with Unix time or converting them to another data structure. Unix time is also used as a mechanism for storing timestamps in a number of [[file systems]], [[file formats]], and [[databases]].

The [[C standard library]] uses Unix time for all date and time functions, and Unix time is sometimes referred to as time_t, the name of the [[data type]] used for timestamps in [[C (programming language)|C]] and [[C++]]. C's Unix time functions are defined as the system time API in the [[POSIX]] specification.<ref>{{cite web |title=The Open Group Technical Standard Base Specifications Issue 7 (2018 edition) |url=https://pubs.opengroup.org/onlinepubs/9699919799/functions/time.html |publisher=IEEE and The Open Group |access-date=1 May 2023 |archive-date=1 May 2023 |archive-url=https://web.archive.org/web/20230501172931/https://pubs.opengroup.org/onlinepubs/9699919799/functions/time.html |url-status=live }}</ref> <!-- TODO reword --> The C standard library is used extensively in all modern desktop operating systems, including [[Microsoft Windows]] and [[Unix-like]] systems such as [[macOS]] and [[Linux]], where it is a standard programming interface.<ref name="windows-unix-time">{{cite web |title=time, _time32, _time64 |url=https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/time-time32-time64?view=msvc-170 |website=learn.microsoft.net | date=13 February 2023 |publisher=Microsoft Corporation |access-date=1 May 2023 |archive-date=1 May 2023 |archive-url=https://web.archive.org/web/20230501184037/https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/time-time32-time64?view=msvc-170 |url-status=live }}</ref><ref>{{cite web |title=The GNU C Library (glibc) |url=https://www.gnu.org/software/libc/ |website=The GNU Operating Sisyem |publisher=Free Software Foundation |access-date=1 May 2023 |quote=The GNU C Library project provides the core libraries for the GNU system and GNU/Linux systems, as well as many other systems that use Linux as the kernel. |archive-date=22 April 2016 |archive-url=https://web.archive.org/web/20160422061403/http://www.gnu.org/software/libc/ |url-status=live }}</ref><ref>{{cite web |title=Mac OS X Manual Page for localtime(3) |url=https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/localtime.3.html |website=Apple Documentation Archive |publisher=Apple Inc. |access-date=1 May 2023 |archive-date=22 July 2022 |archive-url=https://web.archive.org/web/20220722085416/https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/localtime.3.html |url-status=live }}</ref>

[[iOS]] provides a Swift API which defaults to using an epoch of 1&nbsp;January 2001 but can also be used with Unix timestamps.<ref>{{cite web |title=NSDate |url=https://developer.apple.com/documentation/foundation/nsdate |website=Apple Developer Documentation |publisher=Apple Inc. |access-date=1 May 2023 |archive-date=1 May 2023 |archive-url=https://web.archive.org/web/20230501172929/https://developer.apple.com/documentation/foundation/nsdate |url-status=live }}</ref> [[Android (operating system)|Android]] uses Unix time alongside a timezone for its system time API.<ref>{{cite web |title=Time Overview |url=https://source.android.com/docs/core/connect/time |website=Android Open Source Project |publisher=Google LLC |access-date=1 May 2023 |archive-date=1 May 2023 |archive-url=https://web.archive.org/web/20230501172931/https://source.android.com/docs/core/connect/time |url-status=live }}</ref>

Windows does not use Unix time for storing time internally but does use it in system APIs, which are provided in C++ and implement the C standard library specification.<ref name="windows-unix-time" /> Unix time is used in the [[PE format]] for Windows executables.<ref>{{cite web |title=PE Format - Win32 apps |url=https://learn.microsoft.com/en-us/windows/win32/debug/pe-format |website=learn.microsoft.com |date=24 March 2023 |publisher=Microsoft Corporation |access-date=1 May 2023 |language=en-us |archive-date=29 April 2023 |archive-url=https://web.archive.org/web/20230429214701/https://learn.microsoft.com/en-us/windows/win32/debug/pe-format |url-status=live }}</ref>

Unix time is typically available in major programming languages and is widely used in desktop, mobile, and web application programming. [[Java (programming language)|Java]] provides an Instant object which holds a Unix timestamp in both seconds and nanoseconds.<ref>{{cite web |title=Instant (Java Platform SE 8 ) |url=https://docs.oracle.com/javase/8/docs/api/java/time/Instant.html |website=docs.oracle.com |publisher=Oracle |access-date=1 May 2023 |archive-date=25 November 2016 |archive-url=https://web.archive.org/web/20161125045518/http://docs.oracle.com/javase/8/docs/api/java/time/Instant.html |url-status=live }}</ref> [[Python (programming language)|Python]] provides a time library which uses Unix time.<ref>{{citation | url=https://docs.python.org/3/library/time.html | title=time — Time access and conversions | work=Python documentation | accessdate=25 July 2022 | archive-date=22 July 2022 | archive-url=https://web.archive.org/web/20220722022415/https://docs.python.org/3/library/time.html | url-status=live }}</ref> [[JavaScript]] provides a Date library which provides and stores timestamps in milliseconds since the Unix epoch and is implemented in all modern desktop and mobile [[web browsers]] as well as in JavaScript server environments like [[Node.js]].<ref>{{cite web |title=Date - JavaScript {{!}} MDN |url=https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date |website=developer.mozilla.org |publisher=Mozilla |access-date=1 May 2023 |archive-date=21 July 2021 |archive-url=https://web.archive.org/web/20210721082721/https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date |url-status=live }}</ref>

[[Free Pascal]] implements UNIX time with the GetTickCount (deprecated unsigned 32 bit) and GetTickCount64 (Unsigned 64 bit) functions to a resolution of 1ms on [[Unix-like]] platforms.

Filesystems designed for use with Unix-based operating systems tend to use Unix time. [[APFS]], the file system used by default across all Apple devices, and [[ext4]], which is widely used on Linux and Android devices, both use Unix time in nanoseconds for file timestamps.<ref name="apfs">{{citation|url=https://developer.apple.com/support/downloads/Apple-File-System-Reference.pdf|title=Apple File System Reference|page=57|access-date=19 October 2022|quote=This timestamp is represented as the number of nanoseconds since January 1, 1970 at 0:00 UTC, disregarding leap seconds|archive-date=5 November 2022|archive-url=https://web.archive.org/web/20221105082749/https://developer.apple.com/support/downloads/Apple-File-System-Reference.pdf|url-status=live}}</ref><ref>{{cite web |title=Data Structures and Algorithms |url=https://www.kernel.org/doc/html/v4.19/filesystems/ext4/ondisk/index.html#inode-timestamps |website=The Linux Kernel documentation |publisher=Linux Kernel Organization, Inc. |access-date=1 May 2023 |archive-date=1 May 2023 |archive-url=https://web.archive.org/web/20230501193249/https://www.kernel.org/doc/html/v4.19/filesystems/ext4/ondisk/index.html#inode-timestamps |url-status=live }}</ref> Several [[archive file format|archive file formats]] can store timestamps in Unix time, including [[RAR (file format)|RAR]] and [[tar (computing)|tar]].<ref>{{cite web |title=RAR 5.0 archive format |url=https://www.rarlab.com/technote.htm |website=www.rarlab.com |publisher=win.rar GmbH |access-date=1 May 2023 |quote=Time is stored in Unix time_t format if this flags [sic] is set and in Windows FILETIME format otherwise |archive-date=1 May 2023 |archive-url=https://web.archive.org/web/20230501201914/https://www.rarlab.com/technote.htm |url-status=live }}</ref><ref>{{cite web |title=Tape Archive (tar) File Format Family |url=https://www.loc.gov/preservation/digital/formats/fdd/fdd000531.shtml |website=www.loc.gov |publisher=Library of Congress |access-date=1 May 2023 |date=7 January 2021 |archive-date=1 May 2023 |archive-url=https://web.archive.org/web/20230501201909/https://www.loc.gov/preservation/digital/formats/fdd/fdd000531.shtml |url-status=live }}</ref> Unix time is also commonly used to store timestamps in databases, including in [[MySQL]] and [[PostgreSQL]].<ref name="mysql">{{citation|url=https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html|title=Date and Time Functions|work=MySQL 8.0 Reference Manual|accessdate=19 October 2022|archive-date=19 October 2022|archive-url=https://web.archive.org/web/20221019165011/https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html|url-status=live}}</ref><ref>{{cite web |title=8.5. Date/Time Types |url=https://www.postgresql.org/docs/current/datatype-datetime.html |website=PostgreSQL Documentation |publisher=The PostgreSQL Global Development Group |access-date=1 May 2023 |language=en |date=9 February 2023 |archive-date=1 May 2023 |archive-url=https://web.archive.org/web/20230501123216/https://www.postgresql.org/docs/current/datatype-datetime.html |url-status=live }}</ref>