feh 一個基于命令行的高速圖片查看器，非常實用：
 sudo apt-get install feh

 When viewing a slideshow, the following keys may be used:
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 p                      Goto previous slide
 n                       Goto next slide
 r                       Reload image (good for webcams)
 v                      Toggle fullscreen
 m                      Show popup menu
 w                      Size window to current image dimensions
 h                       Pause the slideshow (only useful when using
 <, >                  In place editing, rotate 90 degrees right/left
 <HOME>                 Goto first slide
 <END>                    Goto last slide
 <ESCAPE>              Quit the slideshow
 +, =                          Increase reload delay
 -, _                           Decrease reload delay
 <DELETE>              Remove the currently viewed file from the filelist
 <CTRL+DELETE>         Delete the currently viewed file and remove it from the filelist
 x                                     Close current window
 q                                     Quit the slideshow
 <KEYPAD LEFT>         Move the image to the left
 <KEYPAD RIGHT>       Move the image to the right
 <KEYPAD +>            Zoom in
 <KEYPAD ->             Zoom out
 <KEYPAD *>            Zoom to 100%
 <KEYPAD />             Zoom to fit the window