1. File and Directory Management
| Command | Description |
|---|
| ls | Lists files and directories in the current directory. |
| pwd | Prints the current working directory. |
| cd | Changes the current directory. |
| mkdir <directory> | Creates a new directory. |
| rm <file> | Removes a file. |
| rm -r <directory> | Removes a directory and its contents. |
| cp <source> <destination> | Copies files or directories. |
| mv <source> <destination> | Moves or renames files or directories. |
| touch <file> | Creates an empty file. |
| find <path> -name <filename> | Searches for files by name. |
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2. File Viewing and Editing
| Command | Description |
|---|
| cat <file> | Displays the contents of a file. |
| less <file> | Displays file contents one page at a time. |
| more <file> | Displays file contents one screen at a time. |
| head <file> | Displays the first 10 lines of a file. |
| tail <file> | Displays the last 10 lines of a file. |
| nano <file> | Opens a file in the nano text editor. |
| vi <file> | Opens a file in the vi editor. |
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3. File Permissions
| Command | Description |
|---|
| chmod <permissions> <file> | Changes file permissions. |
| chown <owner>:<group> <file> | Changes file owner and group. |
| ls -l | Lists files with their permissions and ownership. |
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4. System Information
| Command | Description |
|---|
| uname -a | Displays system information. |
| hostname | Displays the system's hostname. |
| uptime | Shows how long the system has been running. |
| whoami | Displays the current user. |
| df -h | Shows disk space usage. |
| free -h | Displays memory usage. |
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5. Process Management
| Command | Description |
|---|
| ps | Lists running processes. |
| top | Displays system tasks and resource usage. |
| kill <PID> | Terminates a process by its Process ID (PID). |
| killall <name> | Terminates all processes by name. |
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6. Networking
| Command | Description |
|---|
| ping <host> | Sends ICMP packets to test network connectivity. |
| ifconfig | Displays network interface information. |
| ip a | Displays IP addresses and interfaces. |
| netstat -tuln | Lists open ports and their listening services. |
| curl <URL> | Fetches content from a URL.
|
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7. Package Management (Centos/Debian/Ubuntu)
| Command | Description |
|---|
| yum update | Updates the package list(Centos). |
| yum install <package> | Installs a package(Centos). |
| yum remove <package> | Removes a package(Centos). |
| apt update | Updates the package list(Debian/Ubuntu). |
| apt install <package> | Installs a package(Debian/Ubuntu). |
| apt remove <package> | Remove a package(Debian/Ubuntu). |
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8. User Management
| Command | Description |
|---|
| adduser <username> | Creates a new user. |
| passwd <username> | Changes a user's password. |
| who | Lists logged-in users. |
| su <username> | Switches to another user account. |
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9. Archiving and Compression
| Command | Description |
|---|
| tar -cvf archive.tar <files> | Archives files. |
| tar -xvf archive.tar | Extracts an archive. |
| gzip <files> | Compresses a file using gzip. |
| gunzip <file.gz> | Decompresses a gzip file. |
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10. System Shutdown and Reboot
| Command | Description |
|---|
shutdown now
OR
init 0 | Shuts down the system immediately. |
reboot
OR
init 6 | Reboots the system. |
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