red hat linux 7 chapter 1

press Ctrl + Alt + F1 to return to the first virtual console and the graphical desktop .
Ctrl + Alt + F2~F6 文字介面

shell basics

#<Command> <Options> <Argument>
       指令              參數         引數(目標)

most command have a --help option
square brackets ,[] , surround optional items
anything followed by ... represents an arbitrary-length list of items of that type
multiple items separated by pipes, | , means only one of them can be specified
text in angle brackets , <> , represents variable data

Red Hat Enteprise Linux 7 system using the GNOME 3 desktop environment to run commands form a shell prompt in a terminal program
GNOME Help  : F1   Applications > Documentation > Help     yelp command



Examples of simple commands

#data

#passwd

#file /etc/passwd 

 //the file command scans the beginning of a file's contents and displays what type it is

#head /etc/passwd   

#tail /etc/passwd

//head and tail commands display the beginning and end of a file respectively

//these commands default display  10  lines

//but have a  -n option that allows a different number of lines to be specified

#wc /etc/passwd 

//the wc command counts lines,words,and characters in a file ,and can take -l,-w,-c option