Java programmers will be commonly used Linux Quick Reference

table of Contents

System Management Services
Document Management
View Log
Compression and decompression
Disk and network management
Firewall
ftp operation
Installation and management software
other

System Management Services

systemctl

Output status of each service system:

systemctl list-units --type=service

View the running status of the service:

systemctl status firewalld

Close Services:

systemctl stop firewalld

Start the service:

systemctl start firewalld

Restart the services (regardless of the current service is started or shut down):

systemctl restart firewalld

Reload the configuration information without interrupting service:

systemctl reload firewalld

Prohibit service boot from the start:

systemctl disable firewalld

Set service boot from the start:

systemctl enable firewalld

Document Management

Find the file
(filename.txt file according to the following name lookup / directory)

find / -name filename.txt

View files, containing hidden files

ls -al

All files are listed in the current directory (/) under:
LS

ls -l /

Gets the current working directory where the absolute path

pwd

Change the current working directory: cd

cd /usr/local

Display or modify the system time and date; date

date '+%Y-%m-%d %H:%M:%S'

To set a user password: passwd

passwd root

Change the user identity (to switch to super user): su

su -username

Clears the screen information

clear

Display help information for the specified command: man

I ls

Discover what the system is run level: who

who -r

Displays the current user logged on to the system:

who -buT

Displays the system memory status (in MB): free

free -m

Dynamic Display System processes running: ps

ps -if

View sshd running dynamic process:

ps -ef | grep sshd

View real-time dynamic process, similar to Windows Task Manager

top

Create a directory

mkdir

Copy the file, including its subfolders to a custom directory

cp -r sourceFolder targetFolder

Delete the directory (this directory is an empty directory)

rmdir deleteEmptyFolder

Delete a file, including its subfolders

rm -rf deleteFile

Delete files: rm

rm text.txt

Moving Files

mv /temp/movefile /targetFolder

Move or overwrite the file: mv

mv oldNameFile.md newNameFile.md

Modify the file permissions (file.java rights -rwxrwxrwx, r for read, w for write, x for executable)

chmod 777 file.java

When the paging file is too long for the view file contents: more
page 10 line view boot.log file

more -c -10 /var/log/boot.log

View Linux boot log file and line number indicate: cat

cat -Ab /var/log/boot.log

Create a file text.txt: touch

touch text.txt

Start Vi editor

vi filename

1) to enter edit mode

shift+i

2) to exit edit mode

esc-->shift+:

3) Save and exit

wq

4) Force Quit

q

View Log

View the first 10 lines of the file

head -n 10 example.txt

10 lines to see the end of file

tail -n 10 example.txt

View the log file (this command will automatically display the new content, the screen only displays 10 lines of content (can be set))

tail -f exmaple.log

less server.log

1) If you want to start the search from the first log line

less server.log -> / search key -> n Find next - one> N Find

2) If you want to start from the last row of the log search

less server.log -> shitf + g ->? Next> N Find - Keyword Search -> Find Next on n

Compression and decompression

Decompression

unzip FileName.zip
compression:
ZIP -r filename.zip DirName

The archive / etc folder of files to the file etc.tar (not compressed): tar

tar -cvf /mydata/etc.tar / etc

File / etc are compressed with gzip folder to the etc.tar.gz:

tar -zcvf /mydata/etc.tar.gz /etc

With bzip2 compressed folder / etc to file /etc.tar.bz2:

tar -jcvf /mydata/etc.tar.bz2 / etc

Page View archive content (gzip):

tar -ztvf /mydata/etc.tar.gz |more -c -10

Unzip the file to the current directory (gzip):

tar -zxvf /mydata/etc.tar.gz

Disk and network management

View Disk Usage

df -h

View disk usage
free

Check disk space occupancy:

df -hT

dh
view the current files and directories under the share folder size:

du -h --max-depth=1 ./*

Displays the current status of network interfaces

ifconfig

View the current routing information: netstat

netstat -rn

View all active TCP connections:

netstat -an

View the system start listening service:

netstat -tulnp

View a port system monitoring services:

netstat -ntlp|grep 8080

View system resources in a connected state:

netstat -atunp

See if there is a certain process

ps -ef | grep java / pid

Download the file from the network

wget

Firewall

There are two Linux firewall software, ConterOS7.0 above using a firewall, ConterOS7.0 the following using iptables, this article will introduce the use of two firewall software.

Firewall

Open the firewall:

systemctl start firewalld

Turn off the firewall:

systemctl stop firewalld

Check firewall status:

systemctl status firewalld

Set boot:

systemctl enable firewalld

Disable boot:

systemctl disable firewalld

Restart the firewall:

firewall-cmd --reload

Open port (after modifying the firewall need to restart to take effect):

firewall-cmd --zone=public --add-port=8080/tcp --permanent

View open ports:

firewall-cmd --list-ports

Close port:

firewall-cmd --zone=public --remove-port=8080/tcp --permanent

Iptables

Installation
Because CenterOS7.0 or later and is not preinstalled Iptables, we need to install.
Turn off the firewall before installing the firewall

Installation iptables:

yum install iptables

Install iptables-services:

yum install iptables-services

Open the firewall:

systemctl start iptables.service

Turn off the firewall:

systemctl stop iptables.service

Check firewall status:

systemctl status iptables.service

Set boot:

systemctl enable iptables.service

Disable boot:

systemctl disable iptables.service

Check the filter table several chain rule (INPUT chain, we can see which ports are open):

iptables -L -n

Check the chain rule NAT table:

iptables -t nat -L -n

Clear all firewall rules:

iptables -F
iptables -X
iptables -Z

To add a rule in the INPUT chain (open port 8080):

iptables -I INPUT -p tcp --dport 8080 -j ACCEPT

Find the line number where the rules:

iptables -L INPUT --line-numbers -n

According to the line number to delete filtering rules (closed 8080):

iptables -D INPUT 1

ftp operation

ftp ip
password password;
bin convert the file into a binary
get get the file name

Installation and management software

rpm

Install the package:

rpm -ivh nginx-1.12.2-2.el7.x86_64.rpm

Fuzzy Search packages:

RPM -qa | grep nginx

Exact Match packages:

RPM -qa nginx

Query Path installation packages:

rpm -ql nginx-1.12.2-2.el7.x86_64

View summary information package:

RPM -qi nginx 1.12.2-2.el7.x86_64

Verify that the package contents and the same installation file:

RPM -V nginx 1.12.2-2.el7.x86_64

Update Package:

rpm -Uvh nginx-1.12.2-2.el7.x86_64

Remove the package:

RPM -e nginx 1.12.2-2.el7.x86_64

yum

Install the package:

yum install nginx

Check the package can be updated:

yum check-update

Updates the specified package:

yum update nginx

Look for package information repository:

yum info nginx*

List all installed packages:

yum info installed

Lists the package name:

yum list nginx*

Fuzzy Search packages:

yum search nginx

other

Terminate the thread (the thread termination position number 19979 thread)

kill -9 19979

View the number of threads (for easy viewing program is wrong)

ps -Lf port number | wc -l

Check network connectivity

ping ip

See ip port connectivity check (connectivity firewall)

telnet ip port -> exit mode shift +] -> quit

Check local ip

ifconfig

View scheduler

crontab -l

Edit Scheduler

crontab -e

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