Summary of the eighth day of Linux operation and maintenance
System important catalogue
/ etc/-Storage profile
/ bin/-storing command files (binaries) can be used by ordinary users
/ sbin/-storing command files (binaries) can be used by root users
/ home/-user home directory slum ordinary user home directory
/ root/-user home directory Imperial root user home directory
/ opt/-save software program data
/ var/-record log information
Important file information of the system
/ etc/
/ usr/-how to install the software (not included with the system)
/ var/-- messages secure
/ proc/-all the data in the directory is stored in memory
System important file information:
/ etc/
1) Network card configuration file
The path where the configuration file is saved is: / etc/sysconfig/network-scripts/ifcfg-eth0
Profile information description:
TYPE=Ethernet-defines the type of network used
BOOTPROTO=none-whether the IP address can be obtained automatically
None/static: will not let the IP address change
Dhcpd: dynamic acquisition of IP addresses
NAME-sets the Nic name information
DEVICE=eth0
ONBOOT=yes-activate the system network card
IPADDR=10.0.0.200-configure IP address information
PREFIX=24-Subnet mask information 255.255.255.0
Determine how many hosts in a LAN can be configured with IP addresses
GATEWAY=10.0.0.254-configure gateway information to allow hosts to access the public network
DNS1=223.5.5.5-access domain name-> ip address information
Visit the domain name of the website, and you can also display whether or not
Can communicate
1) change the configuration file to restart the service:
Restart the network card service mode 1:centos7
Systemctl restart network restarts all network cards
Restart the network card service mode 2:centos7 centos6
/ etc/init.d/network restart restarts all network cards
Restart the Nic service mode 3:
Ifdown (interface down) eth0-stop the eth0 network card
Ifup (interface up) eth0-starts the eth0 network card
Infdown eth0 & & ifup eth0
(used together)
2) address Resolution Service profile
Configuration file save path: / etc/resolv.conf
Profile information description:
Nameserver 223.5.5.5
Supplement: common DNS servers
223.5.5.5Compact 223.6.6.6 offer: Aliyun DNS
114.114.114.114 offer: telecom operator DNS
8.8.8.8 available: Google DNS
Restart network services
The Nic DNS information will be overwritten / synchronized to the resolv.comf file
PS: the configuration file information in the file, which will take effect immediately after the configuration is modified
3) Host name profile *
Server system hostname naming guidelines:
Area name-computer room name-room cabinet
Configuration file save path:
Centos7:/etc/hostname (change the name, you must restart the system to take effect)
Centos6:/etc/sysconfig/network
Temporary adjustment: let the configuration take effect immediately (reconnect) hostname + name
Centos7 can be temporarily modified with permanent changes.
Hostnamectl set-hostname + name
4) resolve the profile locally (establish a relationship between the host name and the IP address) *
Path to save the configuration file: / etc/hosts5) to automatically mount the storage device file *
Configuration file save path: / etc/hosts
Profile information description
① UUID== hardware identification information = = storage file information 6) to enable the system to issue automatic operation commands *
Configuration file save path: / etc/rc.local (permission execution permission)
Profile information description:
How does the profile take effect:
Chmod + x / etc/rc.d/rc.local-add execution permissions to the configuration file
Extension: system scripts (special) make complex / repetitive work-> efficient and simple
How to script ①: for commands
② run script file: sh / path / script file modify script file permissions to execute permissions-/ path / script file
7) system variable or environment variable profile
Configuration file save path: / etc/profile-configuration variable / environment variable / configuration alias information?
Profile information description:
Method 1:
Vi / etc/profile
Last line: export PATH=$PATH:/tmp
Method 2:
Echo export PATH=$PATH:/tmp > > / etc/profile
PS: in an enterprise environment, adding information to a configuration file, adding information using echo must use > > append information
Make the configuration file effective: method one: reproduce the connection server mode two: use the command to load the environment variable configuration file source / etc/profile immediately what is the variable: the script file uses the variable, the flexible use sets the variable: format: variable name = variable value x+y=10 xvariant 5 yearly? Name=oldboy call variable: echo $name script configuration: [root@oldboy66 ~] # cat test.sh name=olddog echo $name 01 echo $name 02 echo $name 03 what are environment variables: 1) variables set in system mode 2) system variables are capitalized how to modify environment variables: PATH temporary modification: export PATH=$PATH:/tmp permanent modification: modify configuration file : / etc/profile command execution principle process: 1) execute the command 2) load the system environment variable $PATH-- > / usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin 3) enter the environment variable specified directory / usr/local/sbin / usr/local/bin / usr/sbin / usr/bin / root/bin / tmp 4) there is a corresponding command file in the specified environment directory-- > execute command operation 4) there is no response command file in the specified environment directory-- > command not found / No such file or directory
Job: how to automatically mount the CD-ROM drive (two ways)
Review how to operate soft and hard connections
