All IT knowledge is the time to rely on the OSI model (TCP / IP four);
:( agreement provisions)
Application layer protocol: http https (B / S) ssh telnet smtp pop3 imap ftp tftp dns dhcp
Transport Layer: tcp udp - port
Network layer: routing protocol is a routing protocol (IPv4 IPv6) xxxx
Data Link Layer: Ethernet protocol MAC ff: ff: ff: ff: ff: ff: ff the world's only
The 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 must be mounted on a Linux system]
to hang in the apparatus umount / mount point
df -h / etc / fstab achieve power automatically mount
/ /bin /sbin /etc /usr /usr/local/ /var /opt /sys /proc /tmp /lib /lib64 /home /root /cdrom /media /mnt
Common file operations on the directory command:
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, packet \ (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
File-related commands
1, create, and delete operations
Touch touch the modification timestamp stat (atime mtime ctime), if the file is not created the file -C MMDDhhmm [CC] YY.ss top
-> View process [CPU: sy ur] -a Rm * find * [range] -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, 2 move files, modify the file name mv ab mv / tmp / a / root / filename extension {} to create a directory name _ Student ID _00001 mkdir {Zhao Zhao, }} _ {00001,00002 Lei Zhao Zhao _00002 _00001 _00001 Lei Lei _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 // tail -n 20 filename simplify: -20 * -f * not exit the file, real-time view file contents head view of the line -n 20 filename simplify // head -n: -20
4. Other
Echo
-e -n echo $PATH
-n // print("Hello World",end='\t') print("Hello World")
print("Hello World")
identifying -e \ t \ n \ r echo -n -e "Hello World \ t" redirect> >> fd file identifier and 0 - Standard Input 1 - Standard Output 2 - error output
= + Program instruction data tag variable
Variable inside the data come from? Code execution and data output to where?
States: the default standard input - output standard keyboard - is used to change the display redirected input and output;
Output redirection> work can not be used to remove this feature set -C redirect the default coverage, while> | can be forced redirection (set + C redirection cover open)
>> append redirection in the original file, additional data can be added;
Extension: 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 store execution status 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 a file empty
（/dev/null） 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 << to multiple lines simultaneously input, the command is used in cat cat >> File << EOF> a> EOF
Error Output Redirection
2> need to bring FD (file identifier)
>> 2 additional error redirect output expansion optimization: cat a.txt> / dev / null cat a.txt 2> / dev / null &> / dev / null command execution, whether correct or not, will be assigned to output content / dev / null & >> [Trivial file] pipe command 1 | comand 2 | command 3 | command 4 | ......... results of the execution of the preceding command output to a later named performed;
[Linux Thought: binding of small features, perform complex function] tail -7 / etc / fstab | cut -d '' -f1 cut cut separator specified -d '' -f 1 taken column 3 1-3
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
If 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 the address 192.168.94.10 netmask 255.255.255.0 gateway 192.168.94.1
2, remote management mechanism Ssh open Ubuntu's ssh port monitoring function;
tcp-22 netstat -tnl // t - tcp Protocol n - is not resolved
If no: apt install openssh-server -y /etc/init.d/ssh start [Ubuntu default can only use ordinary users to connect remotely]
Under ssh [email protected] centos, directly from the root user can remotely log; ssh [email protected]