The command line interface (CLI) is a powerful way to interact with a Linux system. Here are some fundamental commands and concepts to get you started:
1. Navigating the File System:
ls: Lists files and directories.
ls # List all files and directories in the current directory
ls -l # Long listing format with detailed information
ls -a # Include hidden files
cd: Changes the current directory.
cd /path/to/directory # Change to specified directory
cd .. # Move up one directory level
cd ~ # Change to the home directory
cd - # Change to the previous directory
pwd: Displays the present working directory.
pwd # Print the full path of the current directory
2. File Manipulation:
cp: Copies files or directories.
cp source_file destination_file # Copy a file
cp -r source_directory destination_directory # Copy a directory and its contents
mv: Moves or renames files or directories.
mv old_name new_name # Rename a file or directory
mv file /path/to/destination/ # Move a file to a different directory
rm: Removes files or directories.
rm file # Remove a file
rm -r directory # Remove a directory and its contents
rm -i file # Prompt before each file removal
mkdir: Creates a new directory.
mkdir new_directory # Create a new directory
mkdir -p /path/to/new_directory # Create parent directories as needed
rmdir: Removes empty directories.
rmdir directory # Remove an empty directory
touch: Creates an empty file or updates the timestamp of an existing file.
touch new_file # Create an empty file or update the timestamp
3. Viewing and Editing Files:
cat: Concatenates and displays file contents.
cat file # Display the contents of a file
less: Views file contents one page at a time.
less file # View the contents of a file with paging
more: Similar to less, but less feature-rich.
more file # View the contents of a file with paging
nano: Simple text editor.
nano file # Open a file in the nano text editor
vim: Powerful text editor (requires learning basic commands).
vim file # Open a file in the vim text editor
4. File Permissions and Ownership: {see [[File Permission]] for more details}
chmod: Changes file permissions.
chmod 755 file # Set read, write, and execute permissions for owner, and read and execute for group and others
chown: Changes file owner and group.
chown user:group file # Change the owner and group of a file
5. Process Management: {see [[Process Management]] for more details}
ps: Displays information about running processes.
ps # List processes started by the current user
ps aux # List all processes with detailed information
top: Displays real-time system resource usage.
top # Show an interactive view of running processes and system usage
kill: Terminates a process.
kill PID # Terminate a process by its Process ID (PID)
kill -9 PID # Forcefully terminate a process
6. Network Commands: [[Networking Basics]]
ping: Checks network connectivity.
ping google.com # Send ICMP ECHO_REQUEST packets to a network host
ifconfig/ip: Configures network interfaces.
ifconfig # Display network interface information (older tool)
ip addr show # Display network interfaces and addresses (newer tool)
netstat: Displays network connections, routing tables, and interface statistics.
netstat -tuln # List all listening ports and their states
7. System Information:
uname: Displays system information.
uname -a # Show all system information
df: Reports file system disk space usage.
df -h # Display disk space usage in human-readable format
du: Estimates file space usage.
du -sh directory # Show total disk usage of a directory
free: Displays memory usage.
free -h # Show memory usage in human-readable format
These commands form the foundation of interacting with a Linux system through the command line. Mastery of these basics will enable you to perform essential tasks efficiently and pave the way for learning more advanced command-line skills.
NEXT -> User and Group.
BACK -> File System.