Linux System Notes

Basic Commands

1. Find IP address:

   ifconfig

2. View all files in the current directory (including hidden files):

   ls -a

   or

   ll

3. Check memory usage:

   df -h

4. Check memory usage of each file in the current directory:

   du -sh ./*

5. Check if a specific process is running, for example, Nginx,

   ps -ef|grep nginx

6. Kill a running process, for example, Nginx,

   kill -9 <nginx process ID>

7. Another way to kill a running process, for example, Nginx:

   pkill nginx

8. Find files ending with .txt in the /home directory:

   find /home -name "*.txt"

9. Same as above, but ignore case:

   find /home -iname "*.txt"

10. Create a new file command:

    touch a.txt

11. Create a new directory command:

    mkdir ./temp

12. Create a multi-level directory command:

    mkdir -p /home/temp

13. View current path command:

    pwd

14. View system running status:

    top

15. View system information:

    uname -a

16. System reboot command:

    reboot

17. System shutdown command:

    shutdown -t now

18. Shell script execution command:

    ./ a.sh

    or

    sh a.sh

19. Authorization command:

    chmod u+x a.sh

    or

    chmod -R 777 /home/a.sh

    or

    chown -R root:root /home/a.sh

Account Authorization Execution

1. Switch account

   su - root

2. Execute with highest authorization

   sudo command that requires input

Check Network Connectivity

1. Network ping command:

   ping 192.168.1.1

   or

   ping www.baidu.com

2. Network telnet command:

   telnet 192.168.1.1:8080

3. Exit telnet command:

   quit

Remote Connection

1. ssh username@remote server address:

   ssh [email protected]

2. Specify port 2211:

   ssh -p 2211 [email protected]

Note: After entering the

ssh

remote connection command, you will be prompted to enter a password, just enter it to log in.

View Log Notes

1. Dynamic log viewing command:

   tail -f xxx.log

2. The first command can also be abbreviated as:

   tailf xxx.log

3. View the last 10 lines of the log command:

   tail -10 xxx.log

Modify Permissions Notes

1. Modify user and group permissions command:

   chown -R root:root /home

2. Modify a single file or folder command:

   chmod 777 /home

Copy and Move

1. Copy a file to another location:

   cp /home/a.txt /home/temp/a.txt

2. Copy a folder to another location:

   cp -r /home/opt /home/temp

3. Move a file to another location:

   mv /home/a.txt /home/temp

4. Rename a file:

   mv ./a.txt ./b.txt

Delete Files

1. Delete file command:

   rm xxx.txt

2. Delete folder command:

   rm -rf /home

Note:

-r

means recursive, deleting a folder requires deleting each file recursively,

-f

means force execution.

SCP Remote File Transfer

1. Copy a file from remote to local directory

scp [email protected]:/opt/soft/nginx-0.5.38.tar.gz /opt/soft/

Note: The above command downloads the file

nginx-0.5.38.tar.gz

from the

/opt/soft/

directory on the machine

10.10.10.10

to the local directory

/opt/soft/

.

1. Upload local file to specified directory on remote machine

scp /opt/soft/nginx-0.5.38.tar.gz [email protected]:/opt/soft/

1. If SCP has a custom port, such as 2222

scp -rp -P 2222 /opt/soft/nginx-0.5.38.tar.gz [email protected]:/opt/soft/

FTP Commands

1. FTP connection command

ftp -inv username@ip address:port number

1. SFTP connection command

sftp username@ip address:port number

1. Download file from remote to local (download)

ftp> get readme.txt # Download readme.txt file
ftp> mget *.txt     # Download 

1. Upload file from local to remote (upload)

ftp> put /path/readme.txt # Upload readme.txt file
ftp> mput *.txt           # Can upload multiple files

1. Close FTP connection (any of the following three can be used)

bye
exit
quit

Package Management RPM Commands

1. Install RPM package:

   rpm -ivh nginx.rpm

2. Uninstall RPM package:

   rpm -e nginx

3. View all installed RPM packages:

   rpm -qa

4. View RPM packages containing the string

   nginx

   :

   rpm -qa|grep nginx

5. View RPM package installation path:

   rpm -ql nginx

Compression and Decompression

1. Compress tar package:

   tar -zcvf /home/a.tar.gz a.txt

2. Decompress tar package:

   tar -zxvf /home/a.tar.gz /home

3. Compress zip package:

   zip /home/a.zip a.txt

4. Decompress zip package:

   unzip /home/a.zip /home

YUM Commands

1. YUM update package:

   yum update

2. YUM search package:

   yum search nginx

3. YUM install package:

   yum install nginx

4. YUM list all installed packages:

   yum list

5. YUM remove package

yum remove package1                # Remove program package1
yum groupremove group1             # Remove program group group1
yum deplist package1               # View program package1 dependency status

1. YUM clean cache

yum clean packages       # Clean software packages in cache directory
yum clean headers        # Clean headers in cache directory
yum clean oldheaders     # Clean old headers in cache directory

Vim Commands (for example, input:

vim a.txt

)

1. Search command:

   /

2. After searching, find downwards:

   n

   , upwards:

   N

3. Jump to the last line command:

   gg

4. Jump to the first line command:

   GG

5. If you need to input or edit, just press the letter

   i

   .

6. After editing, enter

   :x

   to save, or you can enter

   :wq

   , of course, you must press the

   ESC

   key before entering these commands.

7. Force exit and save command:

   :wq!

8. Force exit without saving command:

   :q!