Ultimate Linux Command Line Cheat Sheet

This cheat sheet provides a comprehensive list of essential Linux commands for system administration, file management, networking, and more.

📌 1. System Information

Command	Description
`uname -a`	Show all system information (kernel, hostname, etc.)
`uname -r`	Display kernel version
`lsb_release -a`	Show Linux distribution details
`uptime`	Display system uptime & load average
`hostname`	Show hostname
`hostname -I`	List all IP addresses
`last reboot`	Show reboot history
`date`	Display current date & time
`cal`	Show calendar
`w`	List logged-in users & their processes
`whoami`	Show current username

🖥️ 2. Hardware Information

Command	Description
`cat /proc/cpuinfo`	Show CPU details
`cat /proc/meminfo`	Display memory information
`free -h`	Show RAM usage (human-readable)
`lspci -tv`	List PCI devices (GPU, network cards, etc.)
`lsusb -tv`	List USB devices
`dmidecode`	Show BIOS & hardware details
`hdparm -i /dev/sda`	Check disk info
`hdparm -tT /dev/sda`	Test disk read speed

📊 3. Performance Monitoring

Command	Description
`top`	Interactive process monitor
`htop`	Enhanced process viewer
`mpstat 1`	Show CPU stats (per core)
`vmstat 1`	Display virtual memory stats
`iostat 1`	Monitor disk I/O stats
`tcpdump -i eth0`	Capture network traffic
`netstat -tuln`	List open ports & services

👥 4. User Management

Command	Description
`id`	Show user & group IDs
`last`	View login history
`who`	List logged-in users
`useradd -m username`	Create a new user
`userdel username`	Delete a user
`usermod -aG groupname username`	Add user to a group
`passwd username`	Change user password

📂 5. File & Directory Commands

Command	Description
`ls -al`	List all files (including hidden)
`pwd`	Show current directory
`mkdir dirname`	Create a directory
`rmdir dirname`	Remove a directory
`rm file`	Delete a file
`rm -rf dirname`	Force-delete a directory
`cp file1 file2`	Copy a file
`cp -r dir1 dir2`	Copy a directory
`mv file1 file2`	Move/rename a file
`ln -s /path linkname`	Create a symlink
`touch file`	Create an empty file
`cat file`	View file contents
`less file`	View file page-by-page
`head -n 5 file`	Show first 5 lines
`tail -f file`	Follow file changes

🔍 6. Searching & Data Manipulation

Command	Description
`grep "text" file`	Search for text in a file
`grep -r "text" /dir`	Recursively search
`find / -name "*.log"`	Find files by name
`locate filename`	Quick file search (updatedb)
`awk '{print $1}' file`	Extract column from text
`sed 's/old/new/g' file`	Replace text in a file
`sort file`	Sort file contents
`diff file1 file2`	Compare two files

⚙️ 7. Process Management

Command	Description
`ps aux`	List all running processes
`kill -9 PID`	Force-kill a process
`killall processname`	Kill all matching processes
`bg`	Send to background
`fg`	Bring to foreground
`nohup command &`	Run after logout

🔒 8. File Permissions

Permission	Meaning	Example
`chmod 755 file`	`rwxr-xr-x` (User: rwx, Group: r-x, Others: r-x)
`chmod 644 file`	`rw-r--r--` (User: rw-, Group: r--, Others: r--)
`chown user:group file`	Change owner & group

🌐 9. Networking

Command	Description
`ifconfig`	Show network interfaces
`ping google.com`	Test connectivity
`dig google.com`	DNS lookup
`netstat -tuln`	List open ports
`ssh user@host`	Connect via SSH
`scp file user@host:/path`	Secure file copy
`wget URL`	Download a file
`curl URL`	Fetch URL content

📦 10. Archives & Compression

Command	Description
`tar -cvf archive.tar dir/`	Create a tar archive
`tar -xvf archive.tar`	Extract tar archive
`tar -czvf archive.tar.gz dir/`	Compress with gzip
`tar -xzvf archive.tar.gz`	Extract gzip archive
`zip archive.zip file`	Create ZIP file
`unzip archive.zip`	Extract ZIP file

📌 11. Package Management

Command	Description
`apt update`	Update package list (Debian/Ubuntu)
`apt install package`	Install a package
`apt remove package`	Remove a package
`yum install package`	Install (RHEL/CentOS)
`dnf install package`	Install (Fedora)
`rpm -i package.rpm`	Install RPM package

💾 12. Disk Usage

Command	Description
`df -h`	Show disk space usage
`du -sh dir/`	Directory size
`fdisk -l`	List partitions
`mount /dev/sda1 /mnt`	Mount a filesystem

💾 13. File Editor

Command	Description
`ex`	Show basic editor
`vi`	visual editor
`nano`	pico clone
`view`	view file only

🚀 Bonus: Shortcuts & Tips

Ctrl + C → Kill current process
Ctrl + Z → Suspend process
Ctrl + D → Exit terminal
!! → Rerun last command
history → View command history

📚 Conclusion

This cheat sheet covers 90% of daily Linux commands. Bookmark it for quick reference!

🔹 For more details: Use man command (e.g., man ls) for full documentation.

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