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I don't know why but after a while I can't add any working ppa any more! When I try this:

sudo add-apt-repository ppa:webupd8team/tor-browser

the output is:

Cannot add PPA: 'ppa:webupd8team/tor-browser'.
Please check that the PPA name or format is correct.

I have ubuntu 13.10 64bit.

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Are you behind a proxy? – i08in Dec 21 '13 at 9:04
really I don't know . Sometimes Ago I install tor-browser and mabye it made the problem . – mahdiar Dec 21 '13 at 9:08
Can you do a sudo apt-get update? If yes, what are the contents of your /etc/apt/apt.conf file? – i08in Dec 21 '13 at 9:29
yes I can . I don't have such file . I have auth.conf . Is it what you are looking for ? – mahdiar Dec 21 '13 at 13:40

Try `sudo apt-get install --reinstall ca-certificates

More info at `

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In addition to configuring proxies, tell sudo to consider the environment with the flag -E

export http_proxy=http://<proxy>:<port>
export https_proxy=http://<proxy>:<port>
sudo -E apt-add-repository ppa:webupd8team/tor-browser

with username and password:

export https_proxy=<username>:<password>@<proxy>:<port>
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