Comprehensive Guide to CentOS VPS: Features,
CentOS VPS (Virtual Private Server) is a widely preferr...
Linux is a powerful and widely used operating system, especially in server environments. Mastering basic Linux commands is essential for system administrators, developers, and anyone working with Linux servers. This guide introduces you to the most important Linux commands, explains what they do, and provides simple usage examples.
1. Navigating the File System
pwd - Print Working Directory
The pwd command shows the current directory you are working in.
Example:
pwd
Output:
/home/user
This indicates that you are in the /home/user directory.
ls - List Files and Directories
The ls command lists all files and directories in your current location.
Example:
ls
You can also use options like -l for detailed output and -a to show hidden files:
ls -la
2. File Management Commands
cd - Change Directory
The cd command allows you to move between directories.
Example:
cd /home/user/Documents
To return to the previous directory, use:
cd ..
To go to your home directory:
cd ~
touch - Create New Files
The touch command creates an empty file.
Example:
touch newfile.txt
This will create an empty file called newfile.txt in the current directory.
cp - Copy Files and Directories
The cp command copies files from one location to another.
Example:
cp file1.txt /home/user/Documents/
This copies file1.txt to the /home/user/Documents/ directory.
mv - Move or Rename Files
The mv command moves or renames files.
Example (Move):
mv file1.txt /home/user/Documents/
Example (Rename):
mv oldname.txt newname.txt
rm - Remove Files and Directories
The rm command deletes files or directories.
Example (Delete a File):
rm file1.txt
Example (Delete a Directory):
rm -r /home/user/old_folder
⚠️ Be cautious when using
rm, as it permanently deletes files.
3. Viewing and Editing Files
cat - View File Content
The cat command displays the contents of a file.
Example:
cat file1.txt
To view large files, use less or more for better navigation.
nano and vim - Edit Text Files
nano: A beginner-friendly text editor.vim: A more advanced editor with powerful features.
Example (Edit file with nano):
nano file1.txt
After editing, press Ctrl + O to save and Ctrl + X to exit.
Example (Edit file with vim):
vim file1.txt
To enter edit mode, press i. To save and exit, press Esc, type :wq, and press Enter.
4. Permissions and Ownership
chmod - Change File Permissions
The chmod command changes file permissions.
Example (Make a File Executable):
chmod +x script.sh
Example (Set Permissions Using Numbers):
chmod 755 file1.txt
Here, 755 represents read, write, and execute permissions for the file owner, and read and execute permissions for others.
chown - Change File Ownership
The chown command changes the owner of a file.
Example:
chown user:group file1.txt
This sets user as the file owner and group as the group owner.
5. System Monitoring Commands
top - View Running Processes
The top command shows system processes, CPU usage, and memory usage.
Example:
top
To exit, press q.
ps - View Active Processes
The ps command shows currently running processes for the current user.
Example:
ps aux
This shows a detailed list of all running processes.
df - Disk Space Usage
The df command displays available disk space.
Example:
df -h
The -h option shows human-readable file sizes (KB, MB, GB).
du - Disk Usage of Files and Directories
The du command shows the disk space used by specific files and directories.
Example:
du -sh /home/user/Documents
This displays the total size of the /home/user/Documents directory.
6. Networking Commands
ping - Test Network Connectivity
The ping command checks if a host is reachable.
Example:
ping google.com
This sends ICMP packets to Google's server and reports the response time.
ifconfig or ip - View Network Interfaces
The ifconfig or ip command shows network interface information.
Example (Ifconfig):
ifconfig
Example (IP command):
ip a
netstat - View Network Connections
The netstat command shows active network connections.
Example:
netstat -tuln
This shows TCP and UDP connections and the ports they are using.
7. User Management
whoami - Display Current User
The whoami command shows the name of the currently logged-in user.
Example:
whoami
adduser and useradd - Create New Users
The adduser and useradd commands create new users.
Example (adduser):
adduser newuser
Example (useradd):
useradd newuser
passwd - Change Password
The passwd command changes a user's password.
Example:
passwd newuser
8. Package Management Commands
apt-get - Install, Update, and Remove Packages
For Debian/Ubuntu systems, apt-get is used to manage packages.
Update Package Lists:
sudo apt-get update
Upgrade Installed Packages:
sudo apt-get upgrade
Install New Package:
sudo apt-get install package_name
Remove Package:
sudo apt-get remove package_name
9. System Shutdown and Restart
shutdown - Shut Down the System
To shut down the system immediately:
sudo shutdown now
To schedule a shutdown after 10 minutes:
sudo shutdown +10
reboot - Restart the System
To reboot the system:
sudo reboot
10. File Compression Commands
tar - Archive Files
The tar command creates and extracts archives.
Create a .tar.gz Archive:
tar -czvf archive.tar.gz /path/to/files
Extract a .tar.gz Archive:
tar -xzvf archive.tar.gz
zip and unzip - Compress and Extract ZIP Files
Create a ZIP File:
zip archive.zip file1.txt file2.txt
Extract a ZIP File:
unzip archive.zip
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