مشکل در نصب برنامه و آپدیت سیستم

[mahdi68]

سلام
من وقتی از دستورات زیر استفاده میکنم خطا های زیر میگیرم

کد: [انتخاب]

mahdi@debian:~$ sudo apt-get update
[sudo] password for mahdi:
Failed to exec method /usr/lib/apt/methods/
Failed to exec method /usr/lib/apt/methods/
E: Method  has died unexpectedly!
E: Sub-process  returned an error code (100)
E: Method /usr/lib/apt/methods/ did not start correctly
E: Method  has died unexpectedly!
E: Sub-process  returned an error code (100)
E: Method /usr/lib/apt/methods/ did not start correctly
mahdi@debian:~$ و یا

کد: [انتخاب]

mahdi@debian:~$ sudo apt-get install firefox
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package firefox is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'firefox' has no installation candidate
mahdi@debian:~$
وقتی در آپدیت منیجر  میخوام بررسی کنم که آپدیت جدیدی هست یا نه خطای زیر میگیرم :

Error message:
Fetch failed: E:Method  has died unexpectedly!, E:Sub-process  returned an error code (100), E:Method /usr/lib/apt/methods/ did not start correctly, E:Method  has died unexpectedly!, E:Sub-process  returned an error code (100), E:Method /usr/lib/apt/methods/ did not start correctly

از دوستان کسی میتونه راهنماییم کنه که چیکار باید بکنم ؟
متشکرم

[-]

سورس لیست رو باز کنید با دستور

کد: [انتخاب]

gedit /etc/apt/sources.list

کد: [انتخاب]

(replace)  deb ://..
(with)     deb http://

[aram]

سلام من دارم printer ام رو نصب میکنم ولی خطاهایی بصورت زیر میده. اشکال چیه؟ کمک کنید!
Running 'sudo apt-get install --assume-yes libcups2-dev'
Please wait, this may take several minutes...
error: Package install command failed with error code 100
Would you like to retry installing the missing package(s) (y=yes*, n=no, q=quit) ?
هرچقدر هم جواب بله بهش میدم باز هم همین چند خط رو میده!

[doomhammer65ir]

کد: [انتخاب]

sudo apt-get install libcups2-dev