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]
The time that your Mac displays is not only for your convenience, but also a requirement for many of OS X's services. This includes its ability to schedule tasks and notify you of calendar events, as well as time-stamp files and events, and properly communicate with online services using some forms of encryption. Windows isn't ready for prime time, so switching to Mac OS isn't going to be any worse. Small armor mac os. Mac OS X is based on Unix. Unix is the most solid, stable and time-tested OS available for any computer costing less than $10,000. The only more 'ready for prime time' OSs are z/OS and AS/400, so unless you're going to buy a mainframe or minicomputer, Unix. Mac OS X shows tremendous promise, which is a nice way of saying that the 10.0 release is not quite ready for prime time. This is most certainly an early adopter's OS release.
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. Reel slots online. 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]
See also[edit]
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)
Start up from macOS Recovery
Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:
Apple silicon
Turn on your Mac and continue to press and hold the power button until you see the startup options window. Click the gear icon labeled Options, then click Continue.
Intel processor
Make sure that your Mac has a connection to the internet. Then turn on your Mac and immediately press and hold Command (⌘)-R Swordsman online download. until you see an Apple logo or other image.
If you're asked to select a user you know the password for, select the user, click Next, then enter their administrator password.
Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:
Apple silicon
Turn on your Mac and continue to press and hold the power button until you see the startup options window. Click the gear icon labeled Options, then click Continue.
Intel processor
Make sure that your Mac has a connection to the internet. Then turn on your Mac and immediately press and hold Command (⌘)-R Swordsman online download. until you see an Apple logo or other image.
If you're asked to select a user you know the password for, select the user, click Next, then enter their administrator password.
Prime Time Masonry And Concrete
Reinstall macOS
Sealevel prototype mac os. A monsters house - ludum dare 33 mac os. Select Reinstall macOS from the utilities window in macOS Recovery, then click Continue and follow the onscreen instructions.
Follow these guidelines during installation:
- If the installer asks to unlock your disk, enter the password you use to log in to your Mac.
- If the installer doesn't see your disk, or it says that it can't install on your computer or volume, you might need to erase your disk first.
- If the installer offers you the choice between installing on Macintosh HD or Macintosh HD - Data, choose Macintosh HD.
- Allow installation to complete without putting your Mac to sleep or closing its lid. Your Mac might restart and show a progress bar several times, and the screen might be empty for minutes at a time.
After installation is complete, your Mac might restart to a setup assistant. If you're selling, trading in, or giving away your Mac, press Command-Q to quit the assistant without completing setup. Then click Shut Down. When the new owner starts up the Mac, they can use their own information to complete setup.
Prime Time Mac Os Catalina
Other macOS installation options
Mac Os Versions
When you install macOS from Recovery, you get the current version of the most recently installed macOS, with some exceptions:
- On an Intel-based Mac: If you use Shift-Option-Command-R during startup, you're offered the macOS that came with your Mac, or the closest version still available. If you use Option-Command-R during startup, in most cases you're offered the latest macOS that is compatible with your Mac. Otherwise you're offered the macOS that came with your Mac, or the closest version still available.
- If the Mac logic board was just replaced, you may be offered only the latest macOS that is compatible with your Mac. If you just erased your entire startup disk, you may be offered only the macOS that came with your Mac, or the closest version still available.
Risen (itch) mac os. You can also use these methods to install macOS, if the macOS is compatible with your Mac:
Prime Time Mac Os X
- Use the App Store to download and install the latest macOS.
- Use the App Store or a web browser to download and install an earlier macOS.
- Use a USB flash drive or other secondary volume to create a bootable installer.
