Hello
@robidson and welcome to linux.org
I’ll answer your questions in reverse.
Does Ubunutu system update only from Internet? (apt-get update)
I guess, but correct me if I'm wrong, Ubuntu does not have repository? All their packags are downloaded from the Internet?
Yes, you have to have your internet connection available, otherwise updates would not be up-to-date.
<apt-get update> is being replaced by <apt update> and <apt-get upgrade> by <apt upgrade>. <apt-get dist-upgrade> by <apt full-upgrade> and so on, however the old ones can still be used.
Ubuntu and its derivatives (eg Linux Mint)
do have Repositories (often referred to as repos). The Ubuntu ones are categorised as
- Main
- Universe
- Restricted
- Multiverse
Then they also have “Other Software” which includes Canonical Partners and their source code, and also software you might add yourself from approved sources. These are derived from PPAs (Personal Package Archives) which you can add to your Repos database, and have updates for same captured in the net of all your other updates.
Ubuntu software can be updated through the following means:
- From CLI (Command Line Interface, eg Terminal) as we have discussed above
- Through your GUI’s Package Manager, called Synaptic Package Manager or SPM or another way of using the GUI point and click style is
- Through the Software Updater, which is possibly the most preferred by Windows/ex-Windows users, because it actively alerts you to updates available by flashing or appearing.
The Software Updater on Ubuntu looks like the small screenshot below
On CentOS
Does RedHat/Centos update only from their local repositories? (using yum update)
Do we have to first, download the repositories from the internet, then yum update?
Of source, it's possible to update from the internet?
My disclaimer here is that I do not currently use CentOS, as I have not been able to get an install to “stick” for me (yet). We have other CentOS users here, and they will likely add information, and correct me if I am wrong.
will clean out the cache from the current release version you are using of CentOS. Follow it with
and your new updates will be downloaded and installed from the CentOS repos.
“Do we have to first, download the repositories from the internet, then yum update?”
… No, you cannot download Repositories, the repos reside on the internet.
The question on source code I will leave to CentOS users, but typically for every Distro from every Family, we can download source code.
If you have further questions in this regard, you could ask away and we will try to help, but let us know as well, whether you have any Linux running, or wish to download and install … in other words, do you have any plans, and if so, what? Then we can better tailor our responses.
Cheers and enjoy
Wizard