In order to update gcc version in my debian pc. I am following this answer but it didn't work for me. [shravan40@ChangeStreet] - [/etc/apt/sources.list.d] - [Mon Oct 24, 13:27][$] <> cat testing.list deb http://ftp.us.debian.org/debian testing main contrib non-free[shravan40@ChangeStreet] - [/etc/apt/sources.list.d] - [Mon Oct 24, 13:27][$] <>[shravan40@ChangeStreet] - [/etc/apt/preferences.d] - [Mon Oct 24, 13:27][$] <> cat testing Package: gccPin: release a=testingPin-Priority: 100[shravan40@ChangeStreet] - [/etc/apt/preferences.d] - [Mon Oct 24, 13:27][$] <> [shravan40@ChangeStreet] - [~] - [Mon Oct 24, 13:30][$] <> sudo apt-get install -t testing gcc[sudo] password for shravan40: Reading package lists... DoneBuilding dependency tree       Reading state information... Donegcc is already the newest version (4:4.9.2-2).0 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.[shravan40@ChangeStreet] - [~] - [Mon Oct 24, 13:30][$] <> 
Unable to update GCC version
debian;gcc
I needed to add , in the end of line 1 of file testing.[shravan40@ChangeStreet] - [/etc/apt/preferences.d] - [Mon Oct 24, 13:27][$] <> cat testing Package: gcc,Pin: release a=testingPin-Priority: 100[shravan40@ChangeStreet] - [/etc/apt/preferences.d] - [Mon Oct 24, 13:27][$] <> 