Time Passed Mac OS

MAC times are pieces of file systemmetadata which record when certain events pertaining to a computer file occurred most recently. The events are usually described as 'modification' (the data in the file was modified), 'access' (some part of the file was read), and 'metadata change' (the file's permissions or ownership were modified), although the acronym is derived from the 'mtime', 'atime', and 'ctime' structures maintained by Unix file systems. Windows file systems do not update ctime when a file's metadata is changed^{[citation needed]}, instead using the field to record the time when a file was first created, known as 'creation time' or 'birth time'. Some other systems also record birth times for files, but there is no standard name for this metadata; ZFS, for example, stores birth time in a field called 'crtime'. MAC times are commonly used in computer forensics.^[1]^[2] The name Mactime was originally coined by Dan Farmer, who wrote a tool with the same name.^[3]

Time Passed Mac Os 11
Time Passed Mac Os Catalina
Mac Os Catalina

The clock in Mac OS X sets itself automatically by default, but if you want to set the precise time or are looking for a command line solution to set system time, you can do so with a tool called ntpdate, or the standard ‘date’ command. Set System Date in Mac OS X from Command Line with a Central Time Server. It took almost 40 minutes on my 2017 iMac 5K which has a really fast SSD. I remember OS updates taking 5-10 minutes even when SSD's were not this fast. And it takes even less time to simply install the OS on an empty disk.

Modification time (mtime)[edit]

A file's modification time describes when the content of the file most recently changed. Because most file systems do not compare data written to a file with what is already there, if a program overwrites part of a file with the same data as previously existed in that location, the modification time will be updated even though the contents did not technically change.

Access time (atime)[edit]

A file's access time identifies when the file was most recently opened for reading. Access times are usually updated even if only a small portion of a large file is examined. A running program can maintain a file as 'open' for some time, so the time at which a file was opened may differ from the time data was most recently read from the file.

Because some computer configurations are much faster at reading data than at writing it, updating access times after every read operation can be very expensive. Some systems mitigate this cost by storing access times at a coarser granularity than other times; by rounding access times only to the nearest hour or day, a file which is read repeatedly in a short time frame will only need its access time updated once.^[4] In Windows, this is addressed by waiting for up to an hour to flush updated access dates to the disk.^[5]

Some systems also provide options to disable access time updating altogether. In Windows, starting with Vista, file access time updating is disabled by default.^[6]

Change time and creation time (ctime)[edit]

Unix and Windows file systems interpret 'ctime' differently:

Unix systems maintain the historical interpretation of ctime as being the time when certain file metadata, not its contents, were last changed, such as the file's permissions or owner (e.g. 'This file's metadata was changed on 05/05/02 12:15pm').
Windows systems use ctime to mean 'creation time'^{[citation needed]} (also called 'birth time') (e.g. 'This file was created on 05/05/02 12:15pm').

This difference in usage can lead to incorrect presentation of time metadata when a file created on a Windows system is accessed on a Unix system and vice versa.^{[citation needed]} Most Unix file systems don't store the creation time, although some, such as HFS+, ZFS, and UFS2 do. NTFS stores both the creation time and the change time.

The semantics of creation times is the source of some controversy.^{[citation needed]} One view is that creation times should refer to the actual content of a file: e.g. for a digital photo the creation time would note when the photo was taken or first stored on a computer. A different approach is for creation times to stand for when the file system object itself was created, e.g. when the photo file was last restored from a backup or moved from one disk to another.

Metadata issues[edit]

As with all file system metadata, user expectations about MAC times can be violated by programs which are not metadata-aware. Some file-copying utilities will explicitly set MAC times of the new copy to match those of the original file, while programs that simply create a new file, read the contents of the original, and write that data into the new copy, will produce new files whose times do not match those of the original.

Some programs, in an attempt to avoid losing data if a write operation is interrupted, avoid modifying existing files. Instead, the updated data is written to a new file, and the new file is moved to overwrite the original. This practice loses the original file metadata unless the program explicitly copies the metadata from the original file. Windows is not affected by this due to a workaround feature called File System Tunneling.^[7]

References[edit]

^Luque, Mark E. (2002). 'Logical Level Analyses of Linux Systems'. In Casey, E. (ed.). Handbook of Computer Crime Investigation: Forensic Tools and Technology. London: Academic Press. pp. 182–183. ISBN0-12-163103-6.
^Sheldon (2002). 'Forensic Analyses of Windows Systems'. In Casey, E. (ed.). Handbook of Computer Crime Investigation: Forensic Tools and Technology. London: Academic Press. pp. 134–135. ISBN0-12-163103-6.
^Dan Farmer (October 1, 2000). 'What Are MACtimes?'. Dr Dobb's Journal.
^'File Times'. Microsoft MSDN Library.
^'File Times'. Microsoft MSDN Library.
^'Disabling Last Access Time in Windows Vista to improve NTFS performance'. The Storage Team at Microsoft.
^'Windows NT Contains File System Tunneling Capabilities'. Microsoft Support.

External links[edit]

Discussion about Windows and Unix timestamps (Cygwin project mailing list)

Retrieved from 'https://en.wikipedia.org/w/index.php?title=MAC_times&oldid=994787883'

Modern computers on a Mac OS are equipped with fast SSDs, which allow you to restart your computer in just a few seconds. Despite this, many users do not restart their computers sometimes for months, sending them to the sleeping mode when they are not needed. This leads to the fact that the memory cache is clogged, and the computer starts to work slower. Sometimes, the user may be surprised finding out for how long he did not restart his computer. There are several ways to view this information on a Mac.

Table of contents:
1. How to determine the running time of a Mac computer
– Via system information
– Via terminal
2. How to determine the total running time on a Mac
3. How to determine the latest Mac reboot dates

Finding out the last reboot time on a Mac, as well as the total operating time, is especially useful if you are buying a used PC.

How to determine the running time of a mac computer

There are two ways to see for how long your Mac computer was running without rebooting.

Via system information

The easiest way implies that you are aware that your computer has a section with system detailed information. Finding it yourself is quite difficult, and you need to know where it is located.

Click on the apple icon in the upper left corner of the screen. You are going to see a drop-down menu, listing the main ways to interact with the computer. As you can see, the top line is “About this Mac”.

Hold down the Option (alt) button on the keyboard, and then the “System Information” line will appear instead of the “About this Mac” line. Click it.

You are going to see the section with details about your computer. Here you need to select the “Software” section in the left menu, where the last line indicates the time the computer has been running since the last boot.

VIA TERMINAL

Every Mac has some kind of Windows command line analogue, called the Terminal. It allows you to execute various commands, including requesting system information. If you know appropriate commands, you should be able to get a lot of useful information about your computer through the Terminal.

To start Terminal, press Command + Space, and enter “Terminal” in the search box, and then select the utility found.

In Terminal, use the uptime command to display information about the system activity time. Details will be displayed in a line with timing.

After you enter the uptime command, there will be also displayed load averages – this is the average load on the computer over the last 1, 5 and 15 minutes.

How to determine the total running time on a mac

In some cases, for example, when buying a used computer, it is useful to find out for how long it has worked with the former owner. Often, sellers are silent about this. You can easily find such information through the “Terminal”. To do this, run it and enter the ac –p command.