Here is a close up shot of Pugsley as he loses his mind because my mother left the room to go outside.
The MESA SDK is a collection of compilers and run-time libraries that make it easy to install and use the MESA stellar evolution code.
- Hopefully, you'll never have to use either the normal or internet Recovery Mode for your Mac, but if you do it's simple to access. For both recovery modes, you will need enough power to see you through the process as well as your Apple ID to reinstall macOS. To start your Mac in Recovery Mode, first, if your Mac is turned off, switch it on.
- Betrayal at Krondor is an MS-DOS-based role-playing video game developed by Dynamix and released by Sierra On-Line in the summer of 1993. Betrayal at Krondor takes place largely in Midkemia, the fantasy world developed by Raymond E. Feist in his Riftwar novels. The game is designed to resemble a book, separated into chapters and narrated in the third-person with a quick-save bookmark feature.
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- A library of over 125,000 free and free-to-try software applications for Mac OS.
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Overview
Experience has demonstrated that incompatibilities and bugs in compilers and libraries are significant obstacles in getting MESA up and running with minimal fuss. For instance, MESA makes use of various features in the new(ish) Fortran 2003 standard, which aren't implemented (or are still buggy) in all but the most recent compiler releases.
To help overcome these obstacles, I've put together a unified software development kit (SDK) which contains compilers and libraries known to compile MESA correctly. The SDK contains the following components:
- The GNU Comipler Collection (gcc), with support for C, C++, and Fortran
- The GNU Project Debugger (gdb)
- The Valgrind code instrumentation framework
- The Basic Linear Algebra Subprogram (BLAS) library
- The Linear Algebra PACKage (LAPACK) library
- The Hierarchical Data Format v5 (HDF5) library
- The PGPLOT graphics library
- The SE library from the NuGrid project
- The ffmpeg movie encoder
- The ndiff fuzzy comparison tool
- Various helper scripts for use in linking against these libraries and other tasks
Currently, both Linux and Mac OS running on Intel/AMD processors are supported. Although the SDK was initially bundled as part of the standard MESA distribution (from release 3708 onwards), it makes more sense to keep it separate. This page hosts all the necessary information and links to download, install and use the SDK.
Linux (Intel)
Compatibility
The SDK should work on any relatively-recent Linux distribution running on 64-bit Intel-compatible processors (32-bit processors are no longer supported; in any case, MESA itself doesn't work on 32-bit). The GNU C library (also known as GLIBC) included in the distribution must be version 2.5 or more recent; to determine what GLIBC your system uses, run the command /lib/libc.so.6 (or, possibly, /lib64/libc.so.6) and examine the first line of the output for the version number.
Prerequisites
The following components must be installed for the SDK to work on Linux-based systems:
- The 'Binutils' development tools
- The 'Make' dependency/compilation tool
- The 'Perl' scripting language
- The 'X11' windowing library plus development headers
- The 'Z' compression library plus development headers
- The 'C' shell or derivatives
Not all of these components are installed by default on some Linux distributions, and you may have to use the appropriate package management tool (e.g., apt-get, yum, rpm, emerge) to install them. The following table lists the package names of the components (and any other pieces that are required) for some of the more-common distributions:
Package | Fedora / CentOS | Ubuntu | Mint | Gentoo | Arch |
---|---|---|---|---|---|
Binutils | binutils | binutils | binutils | sys-devel/binutils | binutils |
Make | make | make | make | sys-devel/make | make |
Perl | perl | perl | perl | dev-lang/perl | perl |
X11 library | libX11, libX11-devel | libx11-6, libx11-dev | libx11-dev | x11-libs/libX11 | libx11 |
Z library | zlib, zlib-devel | zlib1g, zlib1g-dev | zlib-dev | sys-libs/zlib | zlib |
C shell | tcsh | tcsh | tcsh | sys-shells/tcsh | tcsh |
Other | libc6-dev | glibc |
If your distribution is not listed here, please contact me and I'll add it to the table.
Download
To download the SDK for Linux, click on the appropriate link in the table:
Release Date MESA Version at Release | File | Notes |
---|---|---|
April 7 2021 (current) 15140 | mesasdk-x86_64-linux-21.4.1.tar.gz | Added fypp preprocessor; enabled float128 support in mpfr |
December 18 2020 15140 | mesasdk-x86_64-linux-20.12.1.tar.gz | Updated gcc to 10.2 |
March 25 2020 12778 | mesasdk-x86_64-linux-20.3.2.tar.gz | Added ODEPACK library |
March 1 2020 12778 | mesasdk-x86_64-linux-20.3.1.tar.gz | Added math slots functionality |
Note that versions of the SDK older than the current one are not formally supported but are provided here as a courtesy; if you run into problems using an older version, you should first try upgrading to the current version.
Installation
On Linux the SDK can be installed anywhere (this is different from previous releases, where it had to be put in the /opt directory). However, for simplicity the following instructions will assume you're installing in your home directory. Dog surfing prototype mac os. The steps are as follows:
- Download the package from the table above
- Extract it using the command tar xvfz package_name -C ~/ (note that's a tilde in front of the slash!)
- Set the path to the SDK:
- For the C shell: setenv MESASDK_ROOT ~/mesasdk
- For the Bourne shell: export MESASDK_ROOT=~/mesasdk
- Initialize the SDK (also checks compatibility):
- For the C shell: source $MESASDK_ROOT/bin/mesasdk_init.csh
- For the Bourne shell: source $MESASDK_ROOT/bin/mesasdk_init.sh
- Check that the SDK is properly installed by running gfortran --version. The first line of the output should look something like this:
GNU Fortran (GCC) 9.2.0
If it doesn't, then you should consult the Troubleshooting section below.
Steps 3 and 4 need to be repeated each time you begin a new shell session; alternatively, they can be added to the appropriate shell start-up file (~/.cshrc for the C shell, and ~/.profile for the Bourne shell).
Usage
Nothing special needs to be done in order to use the SDK to build MESA. Simply change into the top-level mesa directory (the one created when you download and unpack MESA) and then run ./install.
Mac OS (Intel)
Compatibility
The SDK should work on any relatively-recent OS X distribution (10.10, Yosemite or later) running on Apple computers with 64-bit Intel-compatible processors (32-bit processors are no longer supported; in any case, MESA itself doesn't work on 32-bit).
Prerequisites
The following components must already be installed before the SDK can be installed on Mac OS systems:
- The Xcode command-line tools
- The XQuartz X-windows infrastructure
The Xcode command-line tools can be installed by running xcode-select --install from a Terminal prompt. (Note that a full installation of the Xcode development environment is not necessary). Likewise, XQuartz can downloaded and installed from here. Note that it is often necessary to reinstall the command-line tools and/or XQuartz after upgrading to a new release of OS X.
Download
To download the SDK for Mac OS, click on the appropriate link in the table:
Release Date MESA Version at Release | File | Notes |
---|---|---|
April 7 2021 (current) 15140 | mesasdk-x86_64-macos-21.4.1.pkg | Added fypp preprocessor; enabled float128 support in mpfr |
February 4 2021 15140 | mesasdk-x86_64-macos-21.2.1.pkg | Added support for MacOS 11.2 (Big Sur) |
December 18 2020 15140 | mesasdk-x86_64-macos-20.12.2.pkg | Updated to gcc 10.2 |
December 16 2020 15140 | mesasdk-x86_64-macos-20.12.1.pkg | Added support for MacOS 11.1 (Big Sur) |
November 19 2020 12778 | mesasdk-x86_64-macos-20.11.1.pkg | Added support for MacOS 11.0 (Big Sur) |
September 28 2020 12778 | mesasdk-x86_64-macos-20.9.1.pkg | Fixed 'library not found for -lSystem' issue, arising on fresh Xcode 12 deployments |
April 7 2020 12778 | mesasdk-x86_64-macos-20.4.1.pkg | Added md5sum and other checksum utilities from coreutils |
Note that versions of the SDK older than the current one are not formally supported but are provided here as a courtesy; if you run into problems using an older version, you should first try upgrading to the current version.
Installation
On Mac OS the SDK is installed into the Applications folder; you will likely need Administrator privileges to do this.
- Download the installer from the table above
- Open it by double clicking on it in the Finder
- Follow the on-screen prompts until the installation completes
- Set the path to the SDK:
- For the C shell: setenv MESASDK_ROOT /Applications/mesasdk
- For the Bourne shell: export MESASDK_ROOT=/Applications/mesasdk
- Initialize the SDK (also checks compatibility):
- For the C shell: source $MESASDK_ROOT/bin/mesasdk_init.csh
- For the Bourne shell: source $MESASDK_ROOT/bin/mesasdk_init.sh
- Check that the SDK is properly installed by running gfortran --version. The first line of the output should look something like this:
GNU Fortran (GCC) 10.2.0
If it doesn't, then you should consult the Troubleshooting section below.
Steps 4 and 5 need to be repeated each time you begin a new shell session; alternatively, they can be added to the appropriate shell start-up file (~/.cshrc for the C shell, and ~/.bash_profile for the Bourne shell).
Usage
See the usage instructions above for Linux (they are the same for Mac OS).
Math Slots
It's often convenient to have different versions of the same math libraries available through a single SDK installation — for instance, one optimized for speed, one for accuracy, and so on. To this end, recent releases (>= 20.3.1) of the SDK support a feature known as 'math slots'. By setting the MESASDK_MATH_SLOT environment variable, you can chose which set of math liberaries ('slot') gets used at compile time. Possible choices are as follows:
MESASDK_MATH_SLOT choice | Description |
---|---|
default | Default (no special optimizations or modifications) |
crmath | Correctly-rounded math, via the crlibm library |
If MESASDK_MATH_SLOT is not set, then the default slot is used. Note that when compiling MESA it isn't necessary to set MESASDK_MATH_SLOT yourself; the build scripts take care of it.
Making Movies
To help overcome these obstacles, I've put together a unified software development kit (SDK) which contains compilers and libraries known to compile MESA correctly. The SDK contains the following components:
- The GNU Comipler Collection (gcc), with support for C, C++, and Fortran
- The GNU Project Debugger (gdb)
- The Valgrind code instrumentation framework
- The Basic Linear Algebra Subprogram (BLAS) library
- The Linear Algebra PACKage (LAPACK) library
- The Hierarchical Data Format v5 (HDF5) library
- The PGPLOT graphics library
- The SE library from the NuGrid project
- The ffmpeg movie encoder
- The ndiff fuzzy comparison tool
- Various helper scripts for use in linking against these libraries and other tasks
Currently, both Linux and Mac OS running on Intel/AMD processors are supported. Although the SDK was initially bundled as part of the standard MESA distribution (from release 3708 onwards), it makes more sense to keep it separate. This page hosts all the necessary information and links to download, install and use the SDK.
Linux (Intel)
Compatibility
The SDK should work on any relatively-recent Linux distribution running on 64-bit Intel-compatible processors (32-bit processors are no longer supported; in any case, MESA itself doesn't work on 32-bit). The GNU C library (also known as GLIBC) included in the distribution must be version 2.5 or more recent; to determine what GLIBC your system uses, run the command /lib/libc.so.6 (or, possibly, /lib64/libc.so.6) and examine the first line of the output for the version number.
Prerequisites
The following components must be installed for the SDK to work on Linux-based systems:
- The 'Binutils' development tools
- The 'Make' dependency/compilation tool
- The 'Perl' scripting language
- The 'X11' windowing library plus development headers
- The 'Z' compression library plus development headers
- The 'C' shell or derivatives
Not all of these components are installed by default on some Linux distributions, and you may have to use the appropriate package management tool (e.g., apt-get, yum, rpm, emerge) to install them. The following table lists the package names of the components (and any other pieces that are required) for some of the more-common distributions:
Package | Fedora / CentOS | Ubuntu | Mint | Gentoo | Arch |
---|---|---|---|---|---|
Binutils | binutils | binutils | binutils | sys-devel/binutils | binutils |
Make | make | make | make | sys-devel/make | make |
Perl | perl | perl | perl | dev-lang/perl | perl |
X11 library | libX11, libX11-devel | libx11-6, libx11-dev | libx11-dev | x11-libs/libX11 | libx11 |
Z library | zlib, zlib-devel | zlib1g, zlib1g-dev | zlib-dev | sys-libs/zlib | zlib |
C shell | tcsh | tcsh | tcsh | sys-shells/tcsh | tcsh |
Other | libc6-dev | glibc |
If your distribution is not listed here, please contact me and I'll add it to the table.
Download
To download the SDK for Linux, click on the appropriate link in the table:
Release Date MESA Version at Release | File | Notes |
---|---|---|
April 7 2021 (current) 15140 | mesasdk-x86_64-linux-21.4.1.tar.gz | Added fypp preprocessor; enabled float128 support in mpfr |
December 18 2020 15140 | mesasdk-x86_64-linux-20.12.1.tar.gz | Updated gcc to 10.2 |
March 25 2020 12778 | mesasdk-x86_64-linux-20.3.2.tar.gz | Added ODEPACK library |
March 1 2020 12778 | mesasdk-x86_64-linux-20.3.1.tar.gz | Added math slots functionality |
Note that versions of the SDK older than the current one are not formally supported but are provided here as a courtesy; if you run into problems using an older version, you should first try upgrading to the current version.
Installation
On Linux the SDK can be installed anywhere (this is different from previous releases, where it had to be put in the /opt directory). However, for simplicity the following instructions will assume you're installing in your home directory. Dog surfing prototype mac os. The steps are as follows:
- Download the package from the table above
- Extract it using the command tar xvfz package_name -C ~/ (note that's a tilde in front of the slash!)
- Set the path to the SDK:
- For the C shell: setenv MESASDK_ROOT ~/mesasdk
- For the Bourne shell: export MESASDK_ROOT=~/mesasdk
- Initialize the SDK (also checks compatibility):
- For the C shell: source $MESASDK_ROOT/bin/mesasdk_init.csh
- For the Bourne shell: source $MESASDK_ROOT/bin/mesasdk_init.sh
- Check that the SDK is properly installed by running gfortran --version. The first line of the output should look something like this:
GNU Fortran (GCC) 9.2.0
If it doesn't, then you should consult the Troubleshooting section below.
Steps 3 and 4 need to be repeated each time you begin a new shell session; alternatively, they can be added to the appropriate shell start-up file (~/.cshrc for the C shell, and ~/.profile for the Bourne shell).
Usage
Nothing special needs to be done in order to use the SDK to build MESA. Simply change into the top-level mesa directory (the one created when you download and unpack MESA) and then run ./install.
Mac OS (Intel)
Compatibility
The SDK should work on any relatively-recent OS X distribution (10.10, Yosemite or later) running on Apple computers with 64-bit Intel-compatible processors (32-bit processors are no longer supported; in any case, MESA itself doesn't work on 32-bit).
Prerequisites
The following components must already be installed before the SDK can be installed on Mac OS systems:
- The Xcode command-line tools
- The XQuartz X-windows infrastructure
The Xcode command-line tools can be installed by running xcode-select --install from a Terminal prompt. (Note that a full installation of the Xcode development environment is not necessary). Likewise, XQuartz can downloaded and installed from here. Note that it is often necessary to reinstall the command-line tools and/or XQuartz after upgrading to a new release of OS X.
Download
To download the SDK for Mac OS, click on the appropriate link in the table:
Release Date MESA Version at Release | File | Notes |
---|---|---|
April 7 2021 (current) 15140 | mesasdk-x86_64-macos-21.4.1.pkg | Added fypp preprocessor; enabled float128 support in mpfr |
February 4 2021 15140 | mesasdk-x86_64-macos-21.2.1.pkg | Added support for MacOS 11.2 (Big Sur) |
December 18 2020 15140 | mesasdk-x86_64-macos-20.12.2.pkg | Updated to gcc 10.2 |
December 16 2020 15140 | mesasdk-x86_64-macos-20.12.1.pkg | Added support for MacOS 11.1 (Big Sur) |
November 19 2020 12778 | mesasdk-x86_64-macos-20.11.1.pkg | Added support for MacOS 11.0 (Big Sur) |
September 28 2020 12778 | mesasdk-x86_64-macos-20.9.1.pkg | Fixed 'library not found for -lSystem' issue, arising on fresh Xcode 12 deployments |
April 7 2020 12778 | mesasdk-x86_64-macos-20.4.1.pkg | Added md5sum and other checksum utilities from coreutils |
Note that versions of the SDK older than the current one are not formally supported but are provided here as a courtesy; if you run into problems using an older version, you should first try upgrading to the current version.
Installation
On Mac OS the SDK is installed into the Applications folder; you will likely need Administrator privileges to do this.
- Download the installer from the table above
- Open it by double clicking on it in the Finder
- Follow the on-screen prompts until the installation completes
- Set the path to the SDK:
- For the C shell: setenv MESASDK_ROOT /Applications/mesasdk
- For the Bourne shell: export MESASDK_ROOT=/Applications/mesasdk
- Initialize the SDK (also checks compatibility):
- For the C shell: source $MESASDK_ROOT/bin/mesasdk_init.csh
- For the Bourne shell: source $MESASDK_ROOT/bin/mesasdk_init.sh
- Check that the SDK is properly installed by running gfortran --version. The first line of the output should look something like this:
GNU Fortran (GCC) 10.2.0
If it doesn't, then you should consult the Troubleshooting section below.
Steps 4 and 5 need to be repeated each time you begin a new shell session; alternatively, they can be added to the appropriate shell start-up file (~/.cshrc for the C shell, and ~/.bash_profile for the Bourne shell).
Usage
See the usage instructions above for Linux (they are the same for Mac OS).
Math Slots
It's often convenient to have different versions of the same math libraries available through a single SDK installation — for instance, one optimized for speed, one for accuracy, and so on. To this end, recent releases (>= 20.3.1) of the SDK support a feature known as 'math slots'. By setting the MESASDK_MATH_SLOT environment variable, you can chose which set of math liberaries ('slot') gets used at compile time. Possible choices are as follows:
MESASDK_MATH_SLOT choice | Description |
---|---|
default | Default (no special optimizations or modifications) |
crmath | Correctly-rounded math, via the crlibm library |
If MESASDK_MATH_SLOT is not set, then the default slot is used. Note that when compiling MESA it isn't necessary to set MESASDK_MATH_SLOT yourself; the build scripts take care of it.
Making Movies
The SDK includes the ffmpeg encoder and a simple script, images_to_movie Color by numbers - christmas - free mac os. , which uses ffmpeg to create movies from PNG files produced by MESA.
To illustrate the script in action, suppose the &pgstar section of the MESA inlist file contains the following parameters:
This will make MESA write a sequence of PNG images into the png subdirectory, with filenames grid6_NNNNN.png (where N represents a single digit). To combine these files together into a movie, run the following command from the same directory MESA was run in:
This will produce an MPEG4 movie, with the filename movie.mp4. The type of movie produced is determined from the file extension. Other choices are possible (e.g., mpg for MPEG2), but the images_to_movie.sh script is specifically targeted at producing MPEG4 output, so it might be best to stick with the mp4 extension unless you know what you're doing.
IMPORTANT NOTE: In the example above, the quotes (' ') are necessary to prevent the shell from prematurely expanding the wildcard (*) character.Installing as Root User
If you wish to install the SDK as the root user, that's fine — but you must run the initialization script at least once as root, before you can use the SDK as an ordinary user. This is because configuration files are written into the $MESASDK_ROOT/etc directory on first initialization; and these files must be written as root if you installed as root.
Troubleshooting
If you encounter an error during the build process, please consult the FAQ first. If your problem is not resolved, then you should submit a bug report to the MESA Forum. Be sure to include the following information in your bug report:
- The version of MESA you are trying to build
- The version of the SDK you are using (use the mesasdk_version.sh command to determine this)
- Your platform (machine type, operating system, version)
Mac Os Versions
Also, it would be helpful if you could post the output of the following commands: V slot machines.
- uname -a
- gfortran -v
- echo $MESASDK_ROOT
- echo $PATH
Frequently Asked Questions (FAQ)
Q: When trying to download the SDK using wget, I get the error
A: Our web server is set up to reject requests from wget. As a workaround, add the flag --user-agent=' to your wget invocation.
Q: How can I download the SDK from the command line?
A: Use the wget tool. For instance, to download the Linux version dated YYYYMMDD, run
(See the question above for a discussion of why the --user-agent=' flag is necessary.)
Q: The initialization script produces errors of the sort
A: This is occurring because you installed the SDK as a different user (e.g., root). You must run the initialization script at least once as the installation user, before running as any other user.
Q: When compiling, I'm encountering the error
A: To fix this, set the HDF5_USE_FILE_LOCKING environment variable to FALSE. This can be done via the command
Q: When compiling MESA on MacOS, I'm encountering the error
A: To fix this, uninstall and then re-install the Xcode command line tools via the commands
Then, re-install the SDK.
What is Mac Recovery Mode?
Apple recovery mode is available in an emergency when your macOS is running into serious difficulties. There are four main features of Mac's Recovery Mode, whether that is the regular recovery or internet recovery:
- Restore from Time Machine Backup: Use a previous version of your Mac stored on an external drive. You will have had to prepare this is in advance by connecting an external hard drive and using Time Machine to copy all of your data, including files, OS, and settings. If you have an external copy, you can use this to restore your data under the ‘Restore from Time Machine Backup' in Recovery Mode, which will erase the current disk.
- Reinstall macOS: This wipes your current OS and its data and replaces it with a clean version. If you have any files you need saving, make sure that they've been uploaded to the iCloud or some other storage, whether online or on a separate hard drive. Which version of macOS that is reinstalled may depend on whether you run the normal Recovery Mode or Internet Recovery Mode.
- Get Help Online: Recovery Mode allows you to use Safari to troubleshoot issues you may be experiencing.
- Disk Utility: If you suspect there's something wrong with your drives, you can scan, verify, and repair them from the recovery screen, which might be a quicker and more convenient alternative than erasing and reinstalling your macOS.
Now, if you are considering a complete restart in Recovery or Internet Mode, it's recommended that you give your Mac a thorough clean first. Otherwise, this is like cleaning the house, then dumping everything you've hoovered back onto the carpet. The muck has only been moved around. With a tool like CleanMyMac X, you can declutter everything you don't need, then back up safely (always best doing before restarting or rebooting), which means it should run much faster once restored to full working condition. By the way, this app removes up to 74 GB of junk on an average Mac computer. So, give it a try — you can download CleanMyMac X for free.
The differences between Internet Recovery and regular Recovery
Normal Recovery Mode accesses Recovery HD, an emergency cache of essential utilities that is saved to a partition in your Mac's startup drive, meaning that it's kept separate from the rest of your disk space.
Because it's been partitioned from the rest of your disk space, the data can't be cleared in cleanup scans or manually deleted. It's small (650MB) so it won't affect your Macs performance, but it may be useful if something goes wrong.
If you do need to reinstall your macOS, Recovery Mode will reboot with the most recent version that has been installed on the computer.
Internet Recovery, however, can only reinstall the version of macOS that was originally on your computer when it was new from the box, which likely won't be the most up-to-date version. This is because Internet Recovery uses code embedded into your Mac that includes an image for the appropriate OS. When you begin Internet Recovery, the image is transmitted to the Apple servers to request the correct codes for reinstallation.
Booting from Internet Recovery takes much longer than a normal partition-based recovery and, naturally, requires an internet connection, so ensure your connection is stable and that you have adequate power (keep your Mac charged).
When to use Internet Recovery
If your Mac has been unable to create a partition for the Recovery HD, you will not be able to use normal Recovery Mode. This might be because you're using a RAID volume, which doesn't support the recovery partition, or your drive has been partitioned with Boot Camp Assistant and subsequently modified.
Your Mac may have successfully created the Recovery HD partition but Recovery Mode may not be able to access it. This might be due to damage to the drive or a more serious error in your system.
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If your computer is unable to access normal Recovery Mode, it will automatically begin Internet Recovery. If you have a working recovery partition, you will not be able to access internet Recovery Mode.
How to enter Recovery Mode on Mac
Hopefully, you'll never have to use either the normal or internet Recovery Mode for your Mac, but if you do it's simple to access. For both recovery modes, you will need enough power to see you through the process as well as your Apple ID to reinstall macOS.
1. To start your Mac in Recovery Mode, first, if your Mac is turned off, switch it on. If you're currently using it, hit Restart. You can only use Recovery Mode from the startup drive.
Mac Os Download
2. As soon as you hear the startup chime, hold Command (?) + R.
You will need to hold the keys until a new screen appears.
3. If you have a working recovery partition, you will enter the normal Recovery Mode. The macOS Utilities window appears, which will list the four options to recover your Mac (Restore, Reinstall, Get Help, and Disk Utility). Select Reinstall macOS.
From there, your Mac will be cleared and rebooted with the latest version of macOS that had been installed on it. https://tensoftware.mystrikingly.com/blog/cashier-guy-mac-os.
How to access Internet Recovery Mode
1. Turn on your Mac or restart it as with normal Recovery Mode. As soon as you hear the startup chime, press and hold Command (?) + Option (?) + R.
If your normal Recovery Mode isn't available, pressing Command (?) + R Idocument plus 2 6 mas icloud download free. should automatically redirect you to Internet Recovery mode.
2. After a few seconds, a globe will appear onscreen with the text: Starting Internet Recovery. This may take a while.
Note: This is your computer entering internet Recovery Mode; it is not yet reinstalling OS X.
3. You will then be given a network list to choose your internet connection for the download. Press the check mark to continue or hit Enter once you have selected your network.
4. You will be asked to resubmit the network password even if you have previously connected to it, so make sure you have it available. Hit Enter or the check mark symbol to continue.
5. The screen will then show the image of a globe again, as well as a status bar. This is your computer sending the information about its original state to Apple to request the appropriate drivers and may take some time depending on your internet connection.
6. Once complete, you will see the same Utilities screen as the regular Recovery Mode, which gives you the same options to restore your system.
Mac Recovery Mode: A last resort
It is always worthwhile to run a Disk Utility scan if possible before reinstalling your macOS. It's even better to keep your Mac maintained with regular scans for issues that can accumulate to cause problems. Give your Mac a complete tidy up before restarting in Recovery Mode. Clean out the junk, declutter and restore your beloved Mac to full health.
Caches and system junk quickly build up to clog your system and cause performance problems that might lead you to believe you need to reinstall your macOS, when really all it needs is a thorough clean-out. CleanMyMac X has cleared 737 million GB of junk files that wear down your system and uninstalled 10.5 million unnecessary applications and their forgotten extensions.
CleanMyMac X can also run diagnostics without entering either Mac Recovery Mode, meaning you can fix operating issues before you need to initiate a full reinstall.
Get CleanMyMac X to improve the longterm performance of your Mac!