Estou tentando instalar o software no Ubuntu, mas sempre que escrevo o comando no terminal (por exemplo, sudo apt-get install scalpel ), ele mostra o seguinte erro:
user@OCAC:~$ sudo apt-get install scalpel
[sudo] password for user:
Reading package lists... Done
Building dependency tree
Reading state information... Done
N: Ignoring file 'trusty-stella-datong.volatile' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'trusty-stella-datong.volatile' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
E: Unable to locate package scalpel
Como posso resolver este problema?