C Language Training first day

"1" Open Terminal 1---CTRL + AIT + t//new open a terminal
2---CTRL + SHIFT + n//with open terminal
3---CTRL + SHIFT + t//with "2" Linux @ Ubuntu on open Terminal: ~ $

User name hostname path command prompt ~//home directory = = "/home/linux/
Root directory, the origin of all files under Linux

$//General user Rights
#//Super User privileges

"3" ls
View files under the current path

"4" CD
Path switching

cd//Direct Switch Home directory
CD///switch directly to the root directory
CD directory name//switch to the specified directory
Cd.. Switch to the previous level directory
CD-//switch to the previous catalog

"4" Su
Switch User's commands
SU root//Switch Super User
exit//Exit User

"5" passwd
sudo//Getting temporary Administrator privileges
sudo passwd root//Modify the root user's password

"6" mkdir
mkdir directory Name//create directory
RmDir directory name//delete empty directory

"7" Touch
Touch 1.txt//Create a file

"8" rm
RM 1.txt//Deleting files
RM Directory name-rf//Delete directory

"9" ls
ls-l//Displays the details of the file under the current path as a list
ls-a//View all files (including hidden files)

D rwx rwx r-x 8 linux linux 4096 Mar 12:02 DIR
Type rights link number user name Group name file size time file name

"10" File type (7 types)
The thought of all documents (BCD-LSP)
b//Block device files
c//Character device files
d//Directory
-//Common Files
l//Link File
s//Socket File
p//Pipeline File

"11" File permissions
RWX rwx R-x

r//Readable permissions
w//Writable Permissions
x//Executable Permissions

First group: User's own permissions
Second group: Permissions for members of the same group
Group Three: Other user rights without a relationship

"12"
.. Upper-level path
.//Current path

"13" Echo
echo "Hello"//to Terminal (standard output) output string
echo "ddd0" >>3.txt >> redirect Output

"14" VIM (editor)

1---VI 3.txt
2---Command mode (ESC)
yy//replication
dd//Cut (delete a row)
p//paste
u//Revocation
ctrl+r//Anti-Revocation
gg//cursor moves to the first line of the file
g//cursor moves to the end of the file

Noh Noh Find highlight Cancel

3---Input mode (command mode and input mode)
i//start inserting data from the cursor position
a//inserting data from behind the cursor position
i//inserting data from the first non-whitespace character in the cursor column
a//starting with the cursor at the very back of the line to add data
o//adds a column under the cursor column and enters input mode
o//adds a column above the cursor column and enters input mode

4---Bottom row mode (ESC:)
w//Save
q//exit
wq//Save exit

W! Force Save
q!//forced exit

VSP 1.txt//left and right split screen display
SP 1.txt//Sub-screen display

%s/hello/1234/g//Replace All "Hello" files with "1234"
7,14s/hello/hello/g//Replace the "Hello" in the file 7-14 line with "Hello"
Noh

"15" Cat

Cat 1.txt//Print the contents of the file to the terminal

"16" CP
CP 1.txt filename//File backup
CP 1.txt dirname//Copying files to a different directory

"17" MV
MV 1.txt.. Move a file to the top-level path
MV 2.txt DirName

"18" GCC
1---gcc 1.c//generates a binary a.out by default
./a.out//executing an executable file

2---gcc 1.c-o hello//specifies the output of a hello executable file
./hello

3---Four step full compilation process

Preprocessing: Major macro substitution and the inclusion of a header file to expand
GCC-E Hello.c-o hello.i

Compile: Compile to generate assembly file, check syntax for errors
Gcc-s Hello.i-o Hello.s

Compilation: Compiling assembly files to generate target files (binary files)
Gcc-c Hello.s-o hello.o

Links: link library functions, generating executables
GCC Hello.o-o Hello

4---Two-step compilation process

Compilation: Compiling assembly files to generate target files (binary files)
Gcc-c Hello.c-o hello.o

Links: link library functions, generating executables
GCC Hello.o-o Hello

"19" Numeric representation

Man ascii//view ASCII code table

' 0 ' a ' ~ ' z ' a ' z ' \ n ' Space

48 65~90 97~ 122 10 32

' + ' (end of string flag)
0

difference between uppercase and lowercase characters: 32

"20" Code trace debugging

__LINE__//number of lines where the code is located
The function where the __function__//code resides
The file where the __file__//code resides

C Language Training first day