Load OS onto SD card:
The SD card is the primary storage for the rPi. It contains the Operating System plus all your files and any other software you've installed.
(Unless you use a USB memory stick or drive).
A new SD card needs to have the OS Installed onto the card. This can be done in several ways:
If you buy a new rPi, it may come with an SD card with NOOBS installed on it.
NOOBS is "New-Out-Of-Box-Software."
It is a program that allows you to choose which particular flavor of Raspbian you want to use,
and install it onto the SD card.
Or - you can buy an SD card with NOOBS pre-loaded.
Or - you can download NOOBS onto your own blank SD card.
Or - you can use rPi Imager to install your preferred OS onto a blank SD card.
[Editing in process...
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NOOBS:
The recommended Linux OS for the rPi is contained in NOOBS - "New-Out-Of-Box-Software".
NOOBS is a program residing on the SD card that is the memory/program-space of a rPi.
Upon inserting a new SD card with NOOBS installed and starting up the rPi,
NOOBS will open and give you a choice of which operating system you want to install.
The default/recommended version is Raspbian, which is based on Linux Debian (Ubuntu is also based on Debian)
Most recent version of Raspbian is buster (10), however some of my rPi's use stretch (9).
[If later you want to re-run NOOBS and select something different...]
You can buy an SD card with NOOBS from Adafruit or other vendors,
and often one will come with purchase of a new rPi.
Once you have a good SD card with NOOBS loaded, insert it into a rPi and power up.
Some partition resizing will happen, then a dialog box asking which OS you want to install.
Click the checkbox to select Raspbian, then click Install in the top menu bar
Click Yes to confirm.
At the bottom of the screen is a little menu to let you select the language you want.
I didn't see this until after I'd started the Install, so it will start with default English UK,
probably not the keyboard I want ...
After another few minutes, "Installation Successful" come up. Press Enter to proceed.
After boot-up, select country, language, time-zone, & keyboard, then click "Next"
This page will be a description of how an SD card presents during the process of creating a NOOBS card:
Starting with a new SD card (32gb SanDisk), unformatted (except from mfr):
in Linux tower:
Auto-mounts and File manager opens to: /media/jay/3239-3334
Removable drives shows: 32gb volume
File manager shows: /dev/sdf & /sdf1
$ mount | grep sdf ... shows: /dev/sdf1 on /media/jay/3239-3334 type vfat
$ sudo fdisk -l ... shows (start / end / sectors / size / ID / type:
"/dev/sdf1 8192 62333951 62325760 29.7G c W95 FAT32 (LBA)"
$ sudo fdisk /dev/sdf1 ... p ... shows:
sector size: 512; type: dos
Create partitions:
$ sudo fdisk /dev/sdf1
d ... no partitions defined
n ... p ... 1 ... enter ... enter ...
Linux partition created, 29.7gb
t ... b
partition type changed from Linux to W95 FAT32
w ... enter
same error as before ... fdisk closed
$ sudo fdisk /dev/sdf1 ... p
confirms sdf1p1 partition successfully created
closed terminal, no file manager windows open,
ejected 32gb volume, removed SD card
Inserted SD card in Linux tower:
File manager opens to: /media/jay/3239-3334
Removable drives shows: 32gb volume
File manager shows: /dev/sdf & /sdf1
$ mount | grep sdf ... shows: /dev/sdf1 on /media/jay/3239-3334 type vfat
$ sudo fdisk -l ... shows same as above
$ sudo fdisk /dev/sdf1 ... p ... shows (start / end / sectors / size / ID / type):
/dev/sdf1p1 2048 62325759 62323712 29.7G b W95 FAT32