How to Use a OS X Bootable Installer
Please follow these steps to use the bootable installer:
- Shut down your Mac.
- Press the Power button and hold down Option (⌥).
- You will be in boot menu. Then insert USB memory stick installer.
- Select USB installer and wait for the progress bar to fill.
- Select Disk Utility.
- Select the drive under Internal (your main hard drive)
- Click Erase.
- Give the driver a name; “Macintosh HD” is traditional but you can choose. Ensure that the Format is OS X Extended (Journaled) and the Scheme is GUID Partition Map.
- Click Erase.
- Click Done.
- Choose Disk Utility > Quit Disk Utility
- Select Install OS X and click Continue
- Follow the install OS X options.
- Select Macintosh HD as the installation disk when presented and click Install.
OS X will now be installed on your hard drive from the OS X bootable installer. The whole process can take around half an hour. After this has finished you will have a blank installation of OS X along with a new recovery partition.
How to fix the problem;
You may get the message: “This copy of the install OS X ***** application can’t be verified. It may have been corrupted or tampered with during downloading.” If so, you need to adjust the date and time in OS X. Follow the information in this.
Note: This should work with OS X Mavericks, El Capitan and Sierra
The installer checks the date on the computer. If the date isn’t current, you get the error above. The fix involves correcting the date on your Mac.
If you have an older OS on the Mac
If you have a complete OS on the Mac already, boot into it. Fix the date in the Date & Time system preference (Apple menu > System Preferences). Reboot using the USB boot disk, and you should be able to proceed with the installation.
If you don’t have an OS on the Mac
If you are in a situation like I was, and you don’t have a complete OS on your disk (you reformatted it), you’ll find that there’s no way to access the Date & Time system preference when you use an external USB boot installer drive. The Apple menu doesn’t give you access to System Preferences. You have to use the Terminal to set the date and time.
How to access the Terminal when you boot from an external boot drive installer.
If you use an external boot disk, your Mac starts up into OS X Disk Utilities. You can access the Terminal by clicking on the Utilities menu and selecting Terminal. Once the Terminal has launched, follow these steps:
- At the prompt, type date to see the date that’s on the Mac
- Figure out the numerical representation of the date and time. The pattern you need to follow:
- Month: in two-digit format. For example. July is 07.
- Day: in two-digit format. For example the 7th is 07
- Time: in military format of hours and minutes. For example, 2:00p.m. is 1400
- Year: Last two digits
In my example, today is 02/03/2016 and time 22.05. All you need to do is type command as below to the terminal and hit the enter key.
The date should be set. You can check the date again by typing date at the prompt. You can now run the installer.