review

All IT knowledge is the time to rely on the OSI model (TCP / IP four);
protocol :( provisions)
application layer protocols: http https (B / S) ssh smtp pop3 imap ftp tftp dns dhcp telnet
transport layer: tcp udp - port
network layer: routing protocol is a routing protocol (IPv4 IPv6) xxxx
data link layer: Ethernet protocol ff the MAC: ff: ff: ff: ff: ff: ff globally unique
physical layer: an electrical signal 01

Linux directory structure
Linux disk management
fdisk - partition (logical boundary) writing to the file system; -l disk naming
mkfs -t // Specify the file system format;
Mount To mount the device mount point [Storage Device in Linux ] must be mounted on the system
umount device to be hung in / mount point
DF -H
/ etc / fstab achieve power automatic loading

/ / bin / sbin
/ etc
/ usr / usr / local /
/ var
/ opt
/ SYS / proc
/ tmp
/ lib / lib64
/ Home / root
/ cdrom / Media / mnt

Common command on the directory file operations:
LS file * wildcard globbing [] ^ $?
Cd .. ~ - absolute path and relative path.
Grep

Regular Expressions

1, the string matching [] [^]. [: Digit:] [: alpha:] ...

2, the number of matching *? \ {M \} \ {m, n \} \ {0, n \} \ {m, \}

3, the position of the anchor ^ $ \ b <\ \ b /> 4, grouping \ (ab \) * ABABABAB
ab * abbbbb
*.
-V
-i
^ $ - blank line
mkdir -pv also create multi-level sub-directory
rm -r
rmdir to delete empty directories
tree -L -d

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File-related commands

1, create, and delete operations
Touch touch modification timestamp stat (atime mtime ctime), if the file is not created the file
-C
format of time: MMDDhhmm [CC] YY.ss
Top -> see the process [CPU: sy ur ]
-a
Rm of
* * [range] Find -file d -name a * [file properties]
-exec command} {\;
-OK command} {\;
| xargs command;

Mkdir -pv

2, copy, and move files
Cp - a // carry a copy of all file attributes
Mv move (1). move files

(2) Modify the file name
mv ab
mv / tmp / A / root /
filename extension
{}
to create a directory name _ Student ID Zhao _00001
mkdir {Zhao, Shi Lei} _ {00001,00002}
Zhao _00001
Zhao _00002
Benji _00001
Benji _00002

3, view the file contents
cat-time view of all file contents
cat /etc/init.d/
More // man command
/
?
Q
Less in more clear view large files, we use less
Tail default view countdown 10 lines
-n // 20 -n filename simplify tail: -20
* -f * not exit the file, real-time view file contents
head view of the line
-n 20 filename simplify // head -n: -20

4、其他
Echo -e -n
echo $PATH
-n // print("Hello World",end='\t') print("Hello World")
print("Hello World")
-e 识别 \t \n \r
echo -n -e "Hello World \t"

Redirect> and >>

fd file identifier

0 - standard input

1 - Standard Output

2 - error output

Program instructions = data +

Code variables

Variable inside the data come from? Code execution and data output to where?

States: the default standard input - output standard keyboard - display
redirected is used to change the input and output;

Output redirection:

> Work can not be used to remove this feature set -C redirect the default cover,

At the same time> | can be forced to redirect (set + C to open cover redirection)

>> append redirection in the original file, additional data can be added;

Extended :
In Linux, in addition to the default output command output, it also returns the result of a command execution state;

0 is returned for the command is executed successfully, and returns non-0 is a failure;? $ Name on a stored execution state

Results; at work, we often do not need the results of the command output, but only command execution state,

We will use the redirect will redirect the output to (/ dev / null) empty file

cat a.txt > /dev/null

Input redirection:

<The back of the document, the previous command to be executed;

tr command, the foregoing is replaced with the content of the latter

tr abc ABC < a.txt

<< The multi-line input simultaneously with the cat command

cat >> file << EOF

>EOF

Error output redirection:

2> need to bring FD (file identifier)

>> 2 additional error output redirection

Extended Optimization:

cat a.txt > /dev/null

2 a.txt CAT> / dev / null
&> / dev / null command executed whether correct or not, will be assigned to the content output / dev / null

& >> [Trivial File]

pipeline:

command 1 | comand 2 | command 3 | command 4 | .........

Preceding command execution result, and outputs to later perform a name;

[Linux idea: combine a small function, perform complex functions]

tail -7 /etc/fstab | cut -d' ' -f1

cut cut

-d specified delimiter '

1,3 -f 1 taken column 1-3

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Linux Remote

1, view or configure the network card information

Ethernet and IP addresses

ifconfig

Without this command, we need to install the network tools package (net-tools)

apt install net-tools

Ruoguo, the card is not up, we need to modify the default network card configuration file;

/etc/network/interfaces

vim /etc/network/interfaces

(1) Dynamic - dhcp

auto eth0

iface eth0 inet dhcp

[Modify the configuration file, you need to restart the service]

/etc/init.d/networking restart

(2) Static - to manually configure

address 192.168.94.10

netmask 255.255.255.0

gateway 192.168.94.1

2, remote management mechanism

Ssh ssh port open Ubuntu's monitoring function; tcp-22

netstat -tnl // t - tcp protocol n - not parse

If no: apt install openssh-server -y

/etc/init.d/ssh start

[Ubuntu default can only use ordinary users to connect remotely]

ssh [email protected]

Under centos, directly from the root user can log on remotely;