Cutycapt est une application qui fonctionne en ligne de commande, il permet de réaliser des copies d'écran de site internet.
Pour l'installer:

sudo apt-get install cutycapt

cutycapt --url=http://google.fr --out=google_fr.png

  --help                                Print this help page and exit                
  --url=<url>                           The URL to capture (http:...|file:...|...)   
  --out=<path>                          The target file (.png|pdf|ps|svg|jpeg|...)   
  --out-format=<f>                      Like extension in --out, overrides heuristic 
  --min-width=<int>                     Minimal width for the image (default: 800)   
  --min-height=<int>                    Minimal height for the image (default: 600)  
  --max-wait=<ms>                       Don't wait more than (default: 90000, inf: 0)
  --delay=<ms>                          After successful load, wait (default: 0)     
  --user-style-path=<path>              Location of user style sheet file, if any    
  --user-style-string=<css>             User style rules specified as text           
  --header=<name>:<value>               request header; repeatable; some can't be set
  --method=<get|post|put>               Specifies the request method (default: get)  
  --body-string=<string>                Unencoded request body (default: none)       
  --body-base64=<base64>                Base64-encoded request body (default: none)  
  --app-name=<name>                     appName used in User-Agent; default is none  
  --app-version=<version>               appVers used in User-Agent; default is none  
  --user-agent=<string>                 Override the User-Agent header Qt would set  
  --javascript=<on|off>                 JavaScript execution (default: on)           
  --java=<on|off>                       Java execution (default: unknown)            
  --plugins=<on|off>                    Plugin execution (default: unknown)          
  --private-browsing=<on|off>           Private browsing (default: unknown)          
  --auto-load-images=<on|off>           Automatic image loading (default: on)        
  --js-can-open-windows=<on|off>        Script can open windows? (default: unknown)  
  --js-can-access-clipboard=<on|off>    Script clipboard privs (default: unknown)
  --print-backgrounds=<on|off>          Backgrounds in PDF/PS output (default: off)  
  --zoom-factor=<float>                 Page zoom factor (default: no zooming)       
  --zoom-text-only=<on|off>             Whether to zoom only the text (default: off) 
  --http-proxy=<url>                    Address for HTTP proxy server (default: none)