If you insert an app's installation CD/DVD into your computer and just see an app. Into your Mac (or an external drive if you have a new Mac sans optical disc drive). (Generally, you should choose your Mac's built-in hard drive unless you have a reason to. Book I Chapter 5 You see a badge on the App Store icon on.
Reinstall from macOS Recovery
macOS Recovery makes it easy to reinstall the Mac operating system, even if you need to erase your startup disk first. All you need is a connection to the Internet. If a wireless network is available, you can choose it from the Wi-Fi menu in the menu bar. This menu is also available in macOS Recovery.
1. Start up from macOS Recovery
To start up from macOS Recovery, turn on your Mac and immediately press and hold one of the following combinations on your keyboard. Release the keys when you see an Apple logo, spinning globe, or other startup screen.
Command (⌘)-R
Reinstall the latest macOS that was installed on your Mac (recommended).
Option-⌘-R
Upgrade to the latest macOS that is compatible with your Mac.
Shift-Option-⌘-R
Reinstall the macOS that came with your Mac, or the closest version still available.
You might be prompted to enter a password, such as a firmware password or the password of a user who is an administrator of this Mac. Enter the requested password to continue.
When you see the utilities window, you have started up from macOS Recovery.
2. Decide whether to erase (format) your disk
You probably don't need to erase, unless you're selling, trading in, or giving away your Mac, or you have an issue that requires you to erase. If you need to erase before installing macOS, select Disk Utility from the Utilities window, then click Continue. Learn more about when and how to erase.
3. Install macOS
When you're ready to reinstall macOS, choose Reinstall macOS from the Utilities window. Then click Continue and follow the onscreen instructions. You will be asked to choose a disk on which to install.
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 is for a different version of macOS than you expected, learn about macOS Recovery exceptions.
Please allow installation to complete without putting your Mac to sleep or closing its lid. During installation, your Mac might restart and show a progress bar several times, and the screen might be empty for minutes at a time.
If your Mac restarts to a setup assistant, but you're selling it, trading it in, or giving it away, 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.
macOS Recovery exceptions
The version of macOS offered by macOS Recovery might differ in certain circumstances:
If macOS Sierra 10.12.4 or later has never been installed on this Mac, Option-Command-R installs the macOS that came with your Mac, or the closest version still available. And Shift-Option-Command-R isn't available.
If you erased your entire disk instead of just the startup volume on that disk, macOS Recovery might offer only the macOS that came with your Mac, or the closest version still available. You can upgrade to a later version afterward.
If your Mac has the Apple T2 Security Chip and you never installed a macOS update, Option-Command-R installs the latest macOS that was installed on your Mac.
If you just had your Mac logic board replaced during a repair, macOS Recovery might offer only the latest macOS that is compatible with your Mac.
If you can't get macOS Recovery to offer the installer you want, you might be able to use one of the other ways to install macOS.
Other ways to install macOS
You can also install macOS from the App Store or Software Update preferences. If you can't install macOS Catalina, you might be able to install an earlier macOS, such as macOS Mojave, High Sierra, Sierra, El Capitan, or Yosemite.
Or create a bootable installer disk, then use that disk to install macOS on your Mac or another Mac.
How to create and use a portable version of the Arduino Software (IDE)
This document explains how to make a portable installation of the Arduino Software (IDE) on Windows and Linux machines. A portable installation contains all the files and directories necessary to get the Arduino Software (IDE) to work on a computer without affecting its files outside the folder designated for the portable installation.
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Why portable
Almost in all the schools students don't have administrator privileges, so they don't have write access in some folders. This leads to some problem in using the Arduino Software (IDE) since your preferences and sketchbook are saved in one of those folders. Using a portable version of the IDE you can overcome this problem.
Another scenario can be the following: you want to organize a workshop and you need some additional library or a specific core. Since the portable version stores the sketchbook, the libraries and the hardware folder locally, you can have a starting point equal for all the people who join the workshop just replicating the same folder on all the machines. This is also quite useful if for some reason you don't have an internet connection and want to prepare everything for your project without downloads and delays.
Furthermore, a portable installation could be on a pendrive, allowing you to carry around your personal set of sketches, cores and libraries, to be used on any computer without affecting it with your files.
How to make it portable on Windows and Linux
The procedure is made of a few simple steps. You may use a pendrive or a local folder on your machine. Once done, with libraries and additional cores where needed, that folder can be copied on other machines.
Download a compressed version of the Arduino IDE according to your OS;
Once download has been completed, extract the archive content on the chosen unit (local or pendrive);
Open the extracted folder and in its root create a new directory called portable, alongside the others;
The tree structure should be as this one; the portable folder will be populated by the Arduino Software (IDE) as needed by libraries, sketches and cores.
To use this installation, launch the Arduino executable;
From now on all the sketches, libraries and additional cores will be installed in the portable folder. You can copy the whole main folder and bring it with you anywhere you want: it will retain all your preferences, libraries, cores and sketches.
MacOS / OS X note
The portable installation is not officially supported on Apple's Mac operating systems for several reasons. One of them is related to the package signature (we sign the Arduino IDE package): adding any content - like additional cores, libs and sketches - to the package will break the signature. A consequence of that is the reaction of the Gatekeeper that could even stop the app from starting. This is related to the OS and not to our IDE. Anyway, if you want to experiment you can check this forum thread and try by yourself the solutions developed by the community.
Updating the portable installation
If you want to update a portable installation to a newer version, download the new version in compressed format, then extract the contents in a temporary folder. Now you may either move the 'portable' folder you have from the old installation into the new one, or copy all the files of the new version onto the old one, overwriting all the files. Either way you should end up with the updated portable Arduino Software (IDE) installation with your cores, libraries and sketches preserved. Remember to rename the root folder with the proper release version, if needed.You should always launch the executable file 'Arduino' from inside the folder of your portable installation to use the sketches, cores and libraries contained in it. If you have another installation of the Arduino Software (IDE) on the machine you are using, that version won't be affected. Libraries and cores already installed on the machine won't be seen or used by the portable installation.
Last revision 2018/04/11 by SM
The text of the Arduino getting started guide is licensed under aCreative Commons Attribution-ShareAlike 3.0 License. Code samples in the guide are released into the public domain.