2014-03-25 [筆記] 什麼是PPA ( Personal Package Archive )？

Ubuntu也用了有一陣子，最近發現從 apt-get install 安裝的程式並不是最新的版本。
所以就找了一下如何更新到最新的版本(就拿最有名的VLC為範例吧！)。

How to Install The Latest VLC Release in Ubuntu 12.04

http://www.omgubuntu.co.uk/2014/02/install-latest-vlc-release-ubuntu-12-04

Parental advice out of the way, if the odd bug wouldn’t signal the end of your world you can grab VLC 2.1.x  from thefollowing PPA, maintained by a user called ‘djcj’.

Open a new Terminal and enter the following commands carefully, and type your user password where required.

sudo add-apt-repository ppa:djcj/vlc-stable

sudo apt-get update && sudo apt-get install vlc

這時候就很好奇PPA是什麼？
當下自己亂猜的直覺：連線到別人的電腦下載他包好的程式嗎？

再來就想到，這樣會不會被雷啊？(放病毒之類的)
但後來又想想，其實不就跟apt-get install一樣嗎，只是連線到別人的電腦...

後來上網找了一下PPA，看下面的說明吧！

PPA到底是什麼?

如果你（使用者) 自己打包了一些有用的套件
你可以去 Launchpad 註冊一個專屬帳號
把你打包的套件 上傳到 Launchpad 你的 專屬帳號 內
Launchpad 會幫你轉為 二進位檔 放在 你的專屬套件庫內
如果你對你打包的套件有了更新包
你也可以直接上傳到 Launchpad 你的 專屬帳號 內

這樣 一般的使用者 (像我啦) 只要將你的套件庫 加入到 ubuntu 的 軟體來源 內
就可以 透過 synaptic 下載你打包的套件來安裝或更新

http://www.ubuntu-tw.org/modules/newbb/viewtopic.php?post_id=142156

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What Is An Ubuntu PPA & Why Would I Want To Use One? [Technology Explained]

For example, if a new version of your favorite software comes out you may have to wait until the next version of Ubuntu comes out to try it.

The solution to this is the PPA. This is a repository, provided by Canonical (the company behind Ubuntu), that allows developers and enthusiasts to offer up-to-date versions of software to all Ubuntu users. Originally PPAs were limited to programmers and testers, but Canonical opened PPAs to everyone in late 2007.

Repositories are a more trustworthy way to download software than grabbing EXE files from random websites. Since everything in the default repositories is reviewed by the Ubuntu team before it goes out, you know everything there is completely safe for your system.

That doesn’t mean there aren’t downsides, though. Users typically have to wait for a new version of Ubuntu to try out new software. So if Firefox updates, you might not get to play with the new version until the next Ubuntu release comes out.

This is where PPAs come in. A PPA, or Personal Package Archive, is a collection of software not included in Ubuntu by default. Typically these repositories focus on a single program, but they can include more depending on the person maintaining them. A PPA might focus on an unreleased piece of software, such as Hotot, the best Linux Twitter client out there. It also might include updates for software already in Ubuntu, such as Firefox.

Whatever the case, PPAs provide updates for your favorite software at a much quicker rate than Ubuntu itself. This is great, because you can decide which software you want to keep up to date and leave the rest to Ubuntu.

http://www.makeuseof.com/tag/ubuntu-ppa-technology-explained/

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看完之後其實就跟我當下的第一個直覺想的沒有差太多，因為ubuntu預設新版只會支援六個月，而六個月之後這些套件並不會在維護及更新，但是你(user)又不想要換新版本的ubuntu，可
是又想要使用新版本的套件這時候該怎麼辦？

所以就有了PPA這個機制，讓不想升級的人可以使用第三方的套件做使用。

運作機制就有點像是google play一樣，去申請一個帳號，然後可以把你把包好的新版套件放上去供人下載。

如果我的理解有錯誤還請大家幫忙指證，謝謝！

其他關於PPA的資料：

https://help.launchpad.net/Packaging/PPA

http://www.arthurtoday.com/2010/08/ubuntu-ppa.html#.UzEhgvmSxZx