Day07_ network management, SSH, Shell, and meta-characters

I. Network management

2. Temporarily Modify network configuration
   1. Modify IP Address
      • Ifconfig NIC name IP address
        
   2. Modify DNS
      • vim/etc/resolv.conf: Modify nameserver DNS Address
        
   3. Configure the Gateway
      • Route Add (DEL) default GW gateway address netmask Subnet Mask: temporary set (delete) gateway address
        
      • Route-n Viewing settings
        
   4. Resolving DNS Locally
      1. /etc/hosts/: Locally resolved domain name, in the format: IP address host name
         
      2. Hostname: Querying host names
         
      3. HOSTNAMECTL set-hostname hostname: Set host name
         
4. Configuration file Modify Network configuration
   1. cd/etc/sysconfig/network-scripts/find the native NIC configuration file (e.g. Ens33), Vim Ifcfg-ens33
      
   2. Change the Bootproto to static
      
   3. The following parameters are added below
      • Ipaddr= Local IP
        
      • netmask= Subnet Mask
        
      • gateway= Gateway
        
      • Dns1=dns Address
        • Note that onboot must be yes, or the system will not load this parameter
          
   4. Systemctl Reload Network Reload NIC

Two. SSH Service

1. View ports
   • The Netstat-an:netstat command is used to print the status information of network system in Linux, which can let you know the network situation of the whole Linux system;
     • -A or--all: Displays all sockets in the connection;
       
     • -N or--numeric: Use the IP address directly, not through the domain name server
       
2. Network copy
   • SCP local file path destination IP: Destination path: remote Copy File
     
   • SCP Destination IP: Destination file path Local path: remote download file
     
3. SSH key
   1. Ssh-keygen: Making a remote access authorization key
      
   2. /root/.ssh/: Id_rsa is the key in the current home directory
      
   3. Ssh-copy-id-i Destination IP: Pass the key to the target host Id_rsa.pub
      
4. SSH configuration file
   • /ETC/SSH/SSHD_CONFIG:SSH configuration file

Three. Shell

1. What is a shell?
   • command interpreter, such as bash
     
   • Shell Script
     
2. Command priority
   • ==> Alias: Alias
     
   • ==> Compound Commands:if while for
     
   • ==> function: Functions
     
   • ==> build_in: Built-in
     
   • ==> Hash: View Hash table
     • -R Empty Hash table
       
     • Set: View defined variables and functions
       
     • unset function Name: Delete the definition of the function
       
     • Alias: Defining aliases
       
     • Unalias: Deleting aliases
       
   • ==> $PATH
     
   • ==> Error:command not found
     
3. Read-p ' Print content ' variable (name): Print prompt to print content, wait for input, and store input in Relpay, i.e. name = input
   • read–p "string" var1 var2...varn Note a space between "string" and var1
     
   • Echo & Variables

Four. Meta-characters

1. Special characters in Bash, and special characters that can be knocked out on the keyboard, have a special meaning, emphasizing one thing: metacharacters are interpreted by the shell
   • ': ': The colon is always true

Day07_ network management, SSH, Shell, and meta-characters