Ctrl+c,ctrl+z,ctrl+d

1, CTRL + C Comparison of violence, is to send terminal to the current program, such as you are running a search function, the file is looking for, CTRL + C will force the end of the current process.
2, CTRL + Z is the current program hangs, suspended execution of this program, such as you are in the MySQL terminal, need to come out to do some other file operation, and do not want to quit MySQL terminal (because the next time you have to enter the user name password enter, very troublesome), so you can CTRL + Z hangs the MySQL, then does the other operation, then enters the FG carriage return to be able to return, certainly can suspend many processes to the backstage, then FG adds the number to be able to return the suspended process to the foreground. Of course, it is convenient to switch back and forth with the BG and FG commands.
3, Ctrl+d is to send an exit signal, not so strong, like Ctrl + C operation, such as you from the administrator root back to your ordinary users can use this.