content
- Firewall
View Status
service iptables status
shut down
service iptables stop
turn on
service iptables start
Permanently turn off the firewall
chkconfig iptables off
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2. Common Commands
Of commands
Command + option + parameters
Short options (-): Only one character modification options.
For example: ls -a, of course, a number of short options can be combined, such as tar -cvf
Use a short option letters, but if we can more clearly express the meaning of a word can be used to express the option. Such as ls command has size options, represents the size of the file is displayed. If -size written words, be misunderstood as -s, -i, -z, -e4 options. So then use the long options. In addition, many options are available in both short and long command options, such as
Long options (-): You can modify a single character, a word can also be modified.
cd: Change directory
rm: Delete
-r recursively delete all files
-f Forces are not prompted to delete files
man: Help
ls: Display Directory
-l long format shown in
mkdir: create directory
-p create multi-level directory
vi: Create a file
Command - -help: help get the command
- Shutdown command
Syntax shutdown -h now
Where h is the option indicates time, now represents at once, the command that is immediately shut down the meaning.
- Restart command
Syntax reboot
- Exit command
Syntax exit
- change Password
Syntax passwd
su: switch user
clear: clear screen
ifconfig: Check the local IP
Loading display a file cat
grep: matching string
exercise
- In linux system, what is the super user, what is the difference between them and ordinary users to them.
Users have full access, the user has some privileges, root user management ordinary users
- Open linux system, each directory structure in detail to tell a specific meaning.
/ Boot: the boot loader startup files
/ Lib: binary file
/ Dev: directory contains all Linux external device used in the system
/ Etc: Most storage system configuration files and subdirectories
/ Home: the user's home directory, in addition to the root user are placed in this directory
/ Usr: This directory is the directory system stored procedures, and its larger space. Such as / usr / src stored in the Linux kernel source code, / usr / bin stored in almost all of the executable files. Some programs in / bin or / usr / local / bin in. / Usr / sbin stored in the system management program
/ Root: home directory root system big data management learning exchange group: 251 956 502
- by the linux command and which departments? use a specific command describes the meaning of each part.
Command + option + parameters
- Log in as root, and change their login passwords.
su root
passwd
- To use cat / etc / passwd file contents
cat /etc/passwd
- Show / etc / passwd file in the root user's information
cat /etc/passwd | grep root
- Created in the / usr directory java directory, create a directory jdk8 java directory, create a file manually hello.txt in jdk8 directory. Hello.txt delete files, delete java directory.
mkdir -p java/jdk8
we hello.txt
rm java/jdk8/hello.txt
rm -r java
- Long format display all the files in the / etc directory, change directory in the home directory and then
ls -l /etc
- Baidu inquiry Description ls command files in different colors What is the meaning?
Black: represents a normal file.
Blue: directory,
Green: the executable file.
Light Blue: Link file
×××: device file
- ls in -a, -l is what meaning
-a all
-l long format display
- How to use the command to restart and shutdown?
Reboot: reboot
Shutdown: shutdown -h now
- What command can exit the terminal?
exit
- What is the role grep command is?
Matching string
Common Linux distributions what (answer at least 5)?
Contos, RedHat, red, ubuntu, debian
2. Description of the Linux system characteristics.
- Linux system, which generally consists of four parts?
Hardware, kernel, shell, application
4. Description of the Linux kernel composition.
Memory manager, process manager, device drivers, the virtual file system and network management.
6. How to switch user
su username
7. Displays the current directory
Pwd
8. Switch the main directory
cd/
9.Liunx common directory
/
/usr
/home
/bin
/lib
/root
10. Review the ip address to see whether the Unicom network
Ping domain
- What is a firewall, the firewall command
A firewall is located between the inner barrier and extranets that the system administrator in accordance with pre-defined rules to control access to the data packet. A firewall is a first line of defense system, whose role is to prevent unauthorized users to enter.
View Status
service iptables status
shut down
service iptables stop
turn on
service iptables start
Permanently turn off the firewall
chkconfig iptables off