Use of hotkeys tab, ctrl+c, ctrl+d

1.tab is followed by the first word of a series of commands, it is command completion 
2.tab is followed by the second word of a series of commands, it is file completion 
3.ctrl+c: if input The wrong command or parameter causes the command or program to run continuously under the system. Press ctrl+c to interrupt the current command or program. 
ctrl+d: Indicates the end of keyboard input (End of file), EOF or End of input (end of input), which can replace the input of exit