🐧 Linux Command Sheet

🗂️ File & Directory Commands

Type	Command	Example 1	Example 2
📂 Navigation	cd	cd /var/log – Go to system logs	cd ~/projects – Jump to projects
📋 Listing	ls	ls -l – Long format	ls -lha /etc – All files human-readable
➕ Creation	mkdir	mkdir newdir – Create “newdir”	mkdir -p a/b/c – Nested dirs
📝 Viewing	cat	cat README.md – Dump file	cat file1 file2 – Concat & view
🔍 Searching	find	find . -name "*.log" – Find logs	find /home -size +1M – Files >1 MB
📄 Copy	cp	cp a.txt b.txt – Copy file	cp -r src/ dest/ – Copy dir
🚚 Move	mv	mv old.txt new.txt – Rename	mv *.log archive/ – Move logs
🗑️ Deletion	rm	rm file.txt – Delete file	rm -rf temp/ – Force delete dir
📊 Disk Usage	du	du -h . – Folder sizes	du -sh ~/ – Summarize home
💾 Disk Free	df	df -h – FS usage	df -Th – Type + human
🔗 Linking	ln	ln -s /usr/bin/python3 python – Symlink	ln file.txt hardlink.txt – Hard link

🌐 Network Commands

Type	Command	Example 1	Example 2
📶 Connectivity	ping	ping google.com – Reachability	ping -c3 1.1.1.1 – 3 packets
🛰️ Trace Route	traceroute	traceroute example.com	traceroute -n 8.8.8.8
🌐 HTTP Client	curl	curl https://api.github.com	curl -I https://example.com
⬇️ Download	wget	wget file.tar.gz	wget -qO- https://site.com
🕵️ DNS Lookup	dig	dig +short example.com	dig @8.8.8.8 example.com
🔌 Socket Info	netstat	netstat -tuln	netstat -p
🔌 Socket Info	ss	ss -tuln	ss -p
⚙️ IP Config	ip	ip addr show	ip route show
🔍 Port Scan	nmap	nmap localhost	nmap -sS 192.168.1.0/24

🔐 Permissions Management

Type	Command	Example 1	Example 2
🔑 Modify Mode	chmod	chmod 755 script.sh	chmod -R u+rwX,g-w,o-rwx dir/
👤 Change Owner	chown	chown parvez file.txt	chown -R user:group dir/
🔒 Default Mask	umask	umask 022	umask 077
📜 Get ACL	getfacl	getfacl file.txt	getfacl -R dir/
🛠️ Set ACL	setfacl	setfacl -m u:alice:rw file.txt	setfacl -x g:staff file.txt

🔧 systemd (systemctl)

Type	Command	Example 1	Example 2
ℹ️ Status	systemctl status	systemctl status sshd	systemctl status nginx.service
▶️ Start	systemctl start	systemctl start sshd	systemctl start apache2
⏹️ Stop	systemctl stop	systemctl stop sshd	systemctl stop apache2
🔄 Restart	systemctl restart	systemctl restart sshd	systemctl restart apache2
🛡️ Enable	systemctl enable	systemctl enable sshd	systemctl enable nginx
❌ Disable	systemctl disable	systemctl disable sshd	systemctl disable nginx
🔃 Reload	systemctl daemon-reload	systemctl daemon-reload	systemctl reload-or-restart sshd
📜 List Units	systemctl list-unit-files	systemctl list-unit-files	systemctl list-units --type=service

⚙️ Service Management (`service`)

Type	Command	Example 1	Example 2
ℹ️ Status	service <name> status	service sshd status	service apache2 status
▶️ Start	service <name> start	service sshd start	service apache2 start
⏹️ Stop	service <name> stop	service sshd stop	service apache2 stop
🔄 Restart	service <name> restart	service sshd restart	service apache2 restart
🔃 Reload	service <name> reload	service sshd reload	service apache2 reload

📝 .bashrc Snippets

Type	Snippet	Example 1	Example 2
🔗 Alias	alias	alias ll='ls -la'	alias gs='git status'
🌿 Export	export	export PATH=$PATH:/opt/bin	export EDITOR=vim
🎨 PS1 Prompt 🌟 Click me	PS1	PS1="\u@\h:\w\$ "	PS1=" \[\e[32m\] \u@\h \[\e[m\] :\w\$ "
🏭 Function	mkcd(){ mkdir -p "$1"; cd "$1"; }	mkcd newdir – Make+cd	extract(){ tar -xvf "$1"; }
📜 Source	source	source ~/.bash_aliases	source /etc/bash_completion
🔍 History	HISTSIZE/HISTCONTROL	export HISTSIZE=2000	export HISTCONTROL=ignoredups:erasedups
🔔 Shell Options	shopt	shopt -s histappend	shopt -s globstar