thufir@dur:~$
thufir@dur:~$ ll /etc/apt/sources.list.d/
total 28
drwxr-xr-x 2 root root 4096 Oct 26 05:57 ./
drwxr-xr-x 6 root root 4096 Oct 26 05:52 ../
-rw-r--r-- 1 root root 166 Oct 26 05:57 maarten-fonville-ubuntu-android-studio-artful.list
-rw-r--r-- 1 root root 156 Oct 26 05:57 paolorotolo-ubuntu-android-studio-artful.list
-rw-r--r-- 1 root root 156 Oct 26 05:57 paolorotolo-ubuntu-android-studio-artful.list.save
-rw-r--r-- 1 root root 136 Oct 26 05:57 webupd8team-ubuntu-java-artful.list
-rw-r--r-- 1 root root 136 Oct 26 05:57 webupd8team-ubuntu-java-artful.list.save
thufir@dur:~$
thufir@dur:~$ cat /etc/apt/sources.list.d/paolorotolo-ubuntu-android-studio-artful.list
deb http://ppa.launchpad.net/paolorotolo/android-studio/ubuntu artful main
# deb-src http://ppa.launchpad.net/paolorotolo/android-studio/ubuntu artful main
thufir@dur:~$
thufir@dur:~$ sudo ppa-purge ppa:paolorotolo/android-studio
Updating packages lists
E: The repository 'http://ppa.launchpad.net/paolorotolo/android-studio/ubuntu artful Release' does not have a Release file.
Warning: apt-get update failed for some reason
thufir@dur:~$
thufir@dur:~$ sudo apt update
Get:1 http://security.ubuntu.com/ubuntu artful-security InRelease [70.3 kB]
Hit:2 http://ppa.launchpad.net/maarten-fonville/android-studio/ubuntu artful InRelease
Hit:3 http://ca.archive.ubuntu.com/ubuntu artful InRelease
Get:4 http://ca.archive.ubuntu.com/ubuntu artful-updates InRelease [76.7 kB]
Ign:5 http://ppa.launchpad.net/paolorotolo/android-studio/ubuntu artful InRelease
Hit:6 http://ppa.launchpad.net/webupd8team/java/ubuntu artful InRelease
Hit:7 http://ca.archive.ubuntu.com/ubuntu artful-backports InRelease
Err:8 http://ppa.launchpad.net/paolorotolo/android-studio/ubuntu artful Release
404 Not Found
Reading package lists... Done
E: The repository 'http://ppa.launchpad.net/paolorotolo/android-studio/ubuntu artful Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
thufir@dur:~$
因为它已经日期（显然）。我如何安全地删除这个 ppa？我的意思是使用，ppa-purge因为这似乎是最好的工具。（在语境安装 Android Studio。
答案1
thufir@dur:~$
thufir@dur:~$ sudo add-apt-repository ppa:paolorotolo/android-studio --remove
Automatic builds for Android Studio by Google packaged for Ubuntu.
More info: https://launchpad.net/~paolorotolo/+archive/ubuntu/android-studio
Press [ENTER] to continue or Ctrl-c to cancel removing it.
thufir@dur:~$
thufir@dur:~$ sudo apt-add-repository ppa:maarten-fonville/android-studio --remove
Automatically generated builds of the latest Android Studio
More info: https://launchpad.net/~maarten-fonville/+archive/ubuntu/android-studio
Press [ENTER] to continue or Ctrl-c to cancel removing it.
thufir@dur:~$
thufir@dur:~$ ll /etc/apt/sources.list.d/
total 16
drwxr-xr-x 2 root root 4096 Oct 26 08:46 ./
drwxr-xr-x 6 root root 4096 Oct 26 08:44 ../
-rw-r--r-- 1 root root 0 Oct 26 08:46 maarten-fonville-ubuntu-android-studio-artful.list
-rw-r--r-- 1 root root 0 Oct 26 08:46 maarten-fonville-ubuntu-android-studio-artful.list.save
-rw-r--r-- 1 root root 0 Oct 26 08:46 paolorotolo-ubuntu-android-studio-artful.list
-rw-r--r-- 1 root root 0 Oct 26 08:46 paolorotolo-ubuntu-android-studio-artful.list.save
-rw-r--r-- 1 root root 136 Oct 26 08:46 webupd8team-ubuntu-java-artful.list
-rw-r--r-- 1 root root 136 Oct 26 08:46 webupd8team-ubuntu-java-artful.list.save
thufir@dur:~$
thufir@dur:~$ sudo apt update
Hit:1 http://ca.archive.ubuntu.com/ubuntu artful InRelease
Get:2 http://security.ubuntu.com/ubuntu artful-security InRelease [70.3 kB]
Get:3 http://ca.archive.ubuntu.com/ubuntu artful-updates InRelease [76.7 kB]
Hit:4 http://ppa.launchpad.net/webupd8team/java/ubuntu artful InRelease
Hit:5 http://ca.archive.ubuntu.com/ubuntu artful-backports InRelease
Get:6 http://security.ubuntu.com/ubuntu artful-security/universe amd64 DEP-11 Metadata [2,184 B]
Get:7 http://ca.archive.ubuntu.com/ubuntu artful-updates/main amd64 Packages [9,000 B]
Get:8 http://ca.archive.ubuntu.com/ubuntu artful-updates/main i386 Packages [9,012 B]
Get:9 http://ca.archive.ubuntu.com/ubuntu artful-updates/main amd64 DEP-11 Metadata [8,268 B]
Get:10 http://ca.archive.ubuntu.com/ubuntu artful-updates/universe i386 Packages [4,112 B]
Get:11 http://ca.archive.ubuntu.com/ubuntu artful-updates/universe amd64 Packages [4,116 B]
Get:12 http://ca.archive.ubuntu.com/ubuntu artful-updates/universe amd64 DEP-11 Metadata [2,188 B]
Fetched 186 kB in 1s (179 kB/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
11 packages can be upgraded. Run 'apt list --upgradable' to see them.
thufir@dur:~$
thufir@dur:~$ ll /etc/apt/sources.list.d/
total 16
drwxr-xr-x 2 root root 4096 Oct 26 08:46 ./
drwxr-xr-x 6 root root 4096 Oct 26 08:44 ../
-rw-r--r-- 1 root root 0 Oct 26 08:46 maarten-fonville-ubuntu-android-studio-artful.list
-rw-r--r-- 1 root root 0 Oct 26 08:46 maarten-fonville-ubuntu-android-studio-artful.list.save
-rw-r--r-- 1 root root 0 Oct 26 08:46 paolorotolo-ubuntu-android-studio-artful.list
-rw-r--r-- 1 root root 0 Oct 26 08:46 paolorotolo-ubuntu-android-studio-artful.list.save
-rw-r--r-- 1 root root 136 Oct 26 08:46 webupd8team-ubuntu-java-artful.list
-rw-r--r-- 1 root root 136 Oct 26 08:46 webupd8team-ubuntu-java-artful.list.save
thufir@dur:~$
进而：
thufir@dur:~$
thufir@dur:~$ cd /etc/apt/sources.list.d/
thufir@dur:/etc/apt/sources.list.d$
thufir@dur:/etc/apt/sources.list.d$ ll
total 16
drwxr-xr-x 2 root root 4096 Oct 26 08:46 ./
drwxr-xr-x 6 root root 4096 Oct 26 08:44 ../
-rw-r--r-- 1 root root 0 Oct 26 08:46 maarten-fonville-ubuntu-android-studio-artful.list
-rw-r--r-- 1 root root 0 Oct 26 08:46 maarten-fonville-ubuntu-android-studio-artful.list.save
-rw-r--r-- 1 root root 0 Oct 26 08:46 paolorotolo-ubuntu-android-studio-artful.list
-rw-r--r-- 1 root root 0 Oct 26 08:46 paolorotolo-ubuntu-android-studio-artful.list.save
-rw-r--r-- 1 root root 136 Oct 26 08:46 webupd8team-ubuntu-java-artful.list
-rw-r--r-- 1 root root 136 Oct 26 08:46 webupd8team-ubuntu-java-artful.list.save
thufir@dur:/etc/apt/sources.list.d$
thufir@dur:/etc/apt/sources.list.d$ sudo rm maarten-fonville-ubuntu-android-studio-artful.list
thufir@dur:/etc/apt/sources.list.d$
thufir@dur:/etc/apt/sources.list.d$ sudo rm maarten-fonville-ubuntu-android-studio-artful.list.save
thufir@dur:/etc/apt/sources.list.d$
thufir@dur:/etc/apt/sources.list.d$ sudo rm paolorotolo-ubuntu-android-studio-artful.list
thufir@dur:/etc/apt/sources.list.d$
thufir@dur:/etc/apt/sources.list.d$ sudo rm paolorotolo-ubuntu-android-studio-artful.list.save
thufir@dur:/etc/apt/sources.list.d$
thufir@dur:/etc/apt/sources.list.d$ ll
total 16
drwxr-xr-x 2 root root 4096 Oct 26 08:51 ./
drwxr-xr-x 6 root root 4096 Oct 26 08:44 ../
-rw-r--r-- 1 root root 136 Oct 26 08:46 webupd8team-ubuntu-java-artful.list
-rw-r--r-- 1 root root 136 Oct 26 08:46 webupd8team-ubuntu-java-artful.list.save
thufir@dur:/etc/apt/sources.list.d$
但很好奇为什么ppa-purge不删除那些ppa。