Instale o flameshot no Stretch do Debian

Question

Eu encontrei o programa flameshot e tentei instalá-lo no Debian Stretch, mas recebi a informação

 E: Unable to locate package flameshot 

No site existe a informação

Package for Debian 9 ("Stretch") also available via stretch-backports.

Por favor me diga como instalá-lo via stretch-backports ?

Eu adicionei stretch-backports string em /etc/apt/source.list ao lado de cada stretch main contrib non-free e recebi algum erro enquanto update , mas algumas entradas não apresentaram o erro.

s@lokal:~/Dropbox$ sudo apt update
Ign:1 http://ftp.task.gda.pl/debian stretch InRelease                                                                                                              
Hit:2 http://ftp.task.gda.pl/debian stretch-updates InRelease                                                                                                      
Hit:3 http://ftp.task.gda.pl/debian stretch Release                                                                  
Hit:4 http://security.debian.org/debian-security stretch/updates InRelease                                           
Hit:5 http://nginx.org/packages/debian stretch InRelease                                       
Ign:6 http://dl.google.com/linux/chrome/deb stable InRelease             
Hit:7 http://dl.google.com/linux/chrome/deb stable Release
Hit:8 https://packages.sury.org/php stretch InRelease
Hit:10 https://download.sublimetext.com apt/stable/ InRelease
Hit:11 https://download.sublimetext.com apt/dev/ InRelease
Reading package lists... Done 
E: Failed to fetch http://ftp.task.gda.pl/debian/dists/stretch/InRelease  Unable to find expected entry 'stretch-backports/source/Sources' in Release file (Wrong sources.list entry or malformed file)
E: Failed to fetch http://security.debian.org/debian-security/dists/stretch/updates/InRelease  Unable to find expected entry 'stretch-backports/source/Sources' in Release file (Wrong sources.list entry or malformed file)
E: Failed to fetch http://ftp.task.gda.pl/debian/dists/stretch-updates/InRelease  Unable to find expected entry 'stretch-backports/source/Sources' in Release file (Wrong sources.list entry or malformed file)
E: Some index files failed to download. They have been ignored, or old ones used instead.
s@lokal:~/Dropbox$ 

O problema continua

s@lokal:~/Dropbox$ sudo apt-get install flameshot
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package flameshot
s@lokal:~/Dropbox$ 

Como instalar o flameshot ?

    

Answer 1

Está disponível em backports esticados. link

Adicione o repositório backport.

Atualize, atualize.

Deve então ser instalável