In Linux Nano editor, indenting the selected block back/forth is not recognized by Xshell.
Navigate to Tools -> Key Mapping -> Shift+Up -> Edit
Type : Send String
String : \033[1;2A
Navigate to Tools -> Key Mapping -> Shift+Down -> Edit
Type : Send String
String : \033[1;2B
Navigate to Properties -> Terminal -> Keyboard and select the ‘Use Left ALT key as Meta key’ option