Command	Description
ls	List directory contents
cd	Change directory
pwd	Print working directory
cp source destination	Copy files or directories
mv source destination	Move/rename files or directories
rm file	Remove files
mkdir directory	Create a new directory
rmdir directory	Remove an empty directory
echo "text"	Print text to the terminal
cat file	Concatenate and display file content
less file	View file content one screen at a time
grep "pattern" file	Search for a pattern in a file
find path -name "pattern"	Find files and directories
ps aux	Display currently running processes
kill PID	Kill a process by PID
top	Display and update sorted process list
chmod permissions file	Change file permissions
chown user:group file	Change file owner and group
df -h	Display disk usage in human-readable format
du -sh directory	Display directory size in human-readable format
ln -s target link_name	Create a symbolic link
alias name='command'	Create an alias for a command
export VARIABLE=value	Set an environment variable
history	Show command history
tar -czf archive.tar.gz file	Create a compressed archive using gzip
tar -xzf archive.tar.gz	Extract a compressed archive using gzip
uptime	Show how long the system has been running
whoami	Display the current username
sudo command	Execute a command as the superuser
ssh user@host	Connect to a remote host via SSH
scp source user@host:destination	Copy files over SSH
crontab -e	Edit cron jobs
jobs	List background jobs
bg job_id	Resume a background job
fg job_id	Bring a background job to the foreground
nohup command &	Run a command immune to hangups
diff file1 file2	Compare the contents of two files
source file	Read and execute commands from a file in the current shell

Command	Description
command > file	Redirect standard output (stdout) to a file (overwrite)
command >> file	Redirect standard output (stdout) to a file (append)
command 2> file	Redirect standard error (stderr) to a file (overwrite)
command 2>> file	Redirect standard error (stderr) to a file (append)
command &> file	Redirect both standard output (stdout) and standard error (stderr) to a file (overwrite)
command &>> file	Redirect both standard output (stdout) and standard error (stderr) to a file (append)
command < file	Redirect input from a file
command <<< "string"	Redirect a string as input
command1 \| command2	Use the output of command1 as input for command2 (pipe)
command1 \|& command2	Pipe both stdout and stderr of command1 to command2 (bash 4.0+)
command > /dev/null	Discard standard output (stdout)
command 2> /dev/null	Discard standard error (stderr)
command &> /dev/null	Discard both standard output (stdout) and standard error (stderr)
command > file 2>&1	Redirect stdout to a file and stderr to the same file
command 2>&1 > file	Redirect stderr to the current stdout, then redirect stdout to a file
command1 2>&1 \| command2	Redirect both stdout and stderr of command1 to command2
command > file1 2> file2	Redirect stdout to file1 and stderr to file2
command < file1 > file2	Redirect input from file1 and output to file2
exec > file	Redirect all subsequent stdout in the script to a file
exec 2> file	Redirect all subsequent stderr in the script to a file
exec > /dev/tty	Restore stdout to the terminal
exec 2> /dev/tty	Restore stderr to the terminal
command1 \| tee file	Pipe output of command1 to file and also display it on the terminal
command1 \| tee -a file	Pipe output of command1 to file (append) and also display it on the terminal
command << EOF	Here document: redirect multiple lines of input to a command until EOF
command <<- EOF	Here document with leading tab strip: redirect input until EOF
command <&-	Close standard input (stdin)
command >&-	Close standard output (stdout)
command 2>&-	Close standard error (stderr)

Directory/File	Description
/etc/passwd	User account information
/etc/shadow	Secure user account information (passwords)
/etc/group	Group account information
/etc/gshadow	Secure group account information
/etc/fstab	Filesystem mount table
/etc/hosts	Static table lookup for hostnames
/etc/resolv.conf	DNS server information
/etc/hostname	System's hostname
/etc/sysconfig/network	Basic network configuration
/etc/sysconfig/network-scripts/	Network scripts and configuration files
/etc/crontab	Cron job schedule
/etc/cron.d/	Additional cron job schedules
/etc/ssh/sshd_config	SSH server configuration
/etc/sudoers	sudo configuration file
/etc/systemd/system/	Systemd unit files for services and targets
/etc/selinux/config	SELinux configuration file
/etc/yum.conf	YUM package manager configuration
/etc/yum.repos.d/	Repository configuration files for YUM

Directory/File	Description
/var/log/	Directory containing log files
/var/log/messages	General system log file
/var/log/secure	Security and authentication log
/var/log/audit/	Audit log files
/var/log/dmesg	Kernel ring buffer log
/var/log/httpd/	Apache HTTP server logs
/var/spool/cron/	User crontab files
/var/spool/mail/	User mail files
/var/lib/	Variable state information
/var/lib/mysql/	MySQL database files
/var/lib/pgsql/	PostgreSQL database files
/var/www/html/	Default directory for web server content

Directory/File	Description
/usr/bin/	User binaries
/usr/sbin/	System binaries
/usr/local/	Local software and custom scripts
/usr/share/	Shared data and resources for applications
/usr/lib/	Libraries for binaries in /usr/bin and /usr/sbin
/usr/lib64/	64-bit libraries
/usr/include/	Header files for C programming
/usr/src/	Source code files
/usr/share/doc/	Documentation files for installed packages
/usr/share/man/	Manual pages

Directory/File	Description
/boot/vmlinuz-	Linux kernel image
/boot/initramfs-	Initial RAM filesystem
/boot/grub2/	GRUB 2 bootloader configuration and files
/boot/efi/	EFI boot files

Directory/File	Description
/proc/cpuinfo	CPU information
/proc/meminfo	Memory information
/proc/version	Kernel version
/proc/cmdline	Kernel command line
/proc/devices	Device information
/proc/diskstats	Disk statistics
/proc/uptime	System uptime
/proc/loadavg	System load average
/proc/mounts	Mounted filesystems
/proc/partitions	Partition information
/proc/swaps	Swap space utilization
/proc/sys/	Kernel tunable parameters
/proc/net/	Network status information

Directory/File	Description
/sys/class/	Information about device classes
/sys/block/	Information about block devices
/sys/fs/	Filesystem information
/sys/kernel/	Kernel information and tunable parameters
/sys/module/	Information about loaded kernel modules
/sys/devices/	Information about devices

Directory/File	Description
/dev/sda	First SCSI disk drive
/dev/sdb	Second SCSI disk drive
/dev/tty	Terminal devices
/dev/null	Null device (discard output)
/dev/random	Random number generator
/dev/urandom	Non-blocking random number generator

Command	Description
i	Enter insert mode
Esc	Exit insert mode
:w	Save the file
:q	Quit Vim
:wq	Save and quit Vim
:q!	Quit without saving
:e filename	Open a file
:n	Open the next file
:p	Open the previous file
/pattern	Search for a pattern
n	Repeat the last search
N	Repeat the last search in the opposite direction
:s/old/new/g	Replace all occurrences of old with new in the current line
:%s/old/new/g	Replace all occurrences of old with new in the file
yy	Yank (copy) the current line
p	Paste the yanked text
dd	Delete the current line
u	Undo the last action
Ctrl-r	Redo the last undone action
gg	Go to the first line of the file
G	Go to the last line of the file
0	Go to the beginning of the line
$	Go to the end of the line
dG	Delete from the current line to the end of the file
v	Enter visual mode
V	Enter visual line mode
Ctrl-v	Enter visual block mode
:help	Open Vim help
:!command	Execute an external command
:r !command	Read the output of a command into the current file
:set number	Show line numbers
:set nonumber	Hide line numbers
:syntax on	Enable syntax highlighting
:syntax off	Disable syntax highlighting

Command	Description
tmux new -s session_name	Create a new session named session_name
tmux attach -t session_name	Attach to an existing session named session_name
tmux list-sessions	List all sessions
tmux kill-session -t session_name	Kill the session named session_name
tmux new-window -n window_name	Create a new window named window_name
tmux split-window -h	Split the current window horizontally
tmux split-window -v	Split the current window vertically
tmux select-pane -t :0	Select pane 0
tmux resize-pane -L	Resize the current pane to the left
tmux resize-pane -R	Resize the current pane to the right
tmux resize-pane -U	Resize the current pane upwards
tmux resize-pane -D	Resize the current pane downwards
tmux kill-pane -t pane_number	Kill the pane with the specified pane_number
tmux list-windows	List all windows in the current session
tmux kill-window -t window_number	Kill the window with the specified window_number
tmux rename-window new_name	Rename the current window to new_name
tmux list-panes	List all panes in the current window
tmux swap-pane -s pane1 -t pane2	Swap the position of pane1 and pane2
tmux move-pane -t target_pane	Move the current pane to target_pane
tmux set-option -g prefix C-a	Change the prefix key to Ctrl-a
tmux bind-key [key] [command]	Bind a key to a tmux command
tmux unbind-key [key]	Unbind a key from a tmux command
tmux source-file ~/.tmux.conf	Reload the tmux configuration file
tmux save-buffer ~/buffer.txt	Save the tmux paste buffer to a file
tmux show-options -g	Show all global options
tmux display-message "message"	Display a message in the status line
tmux clock-mode	Enter clock mode in the current pane
tmux list-keys	List all key bindings
tmux capture-pane -S -100	Capture the last 100 lines of the current pane
tmux show-environment	Show the tmux environment variables
tmux detach-client -t session_name	Detach the client from session_name
tmux rename-session new_session_name	Rename the current session to new_session_name
tmux rotate-window -U	Rotate the current window upwards
tmux rotate-window -D	Rotate the current window downwards
tmux list-clients	List all clients
tmux select-layout even-horizontal	Arrange panes in an even horizontal layout
tmux select-layout even-vertical	Arrange panes in an even vertical layout
tmux select-layout tiled	Arrange panes in a tiled layout

Hotkey	Description
Ctrl-b	Default prefix key (can be changed)
Ctrl-b ?	List all key bindings
Ctrl-b d	Detach from the current session
Ctrl-b c	Create a new window
Ctrl-b ,	Rename the current window
Ctrl-b w	List all windows
Ctrl-b n	Move to the next window
Ctrl-b p	Move to the previous window
Ctrl-b l	Move to the last (previously active) window
Ctrl-b &	Kill the current window
Ctrl-b %	Split the current pane vertically
Ctrl-b "	Split the current pane horizontally
Ctrl-b x	Kill the current pane
Ctrl-b o	Switch to the next pane
Ctrl-b ;	Switch to the last active pane
Ctrl-b q	Display pane numbers
Ctrl-b z	Toggle pane zoom
Ctrl-b {	Swap pane with the previous pane
Ctrl-b }	Swap pane with the next pane
Ctrl-b Space	Toggle through layouts
Ctrl-b Ctrl-o	Rotate panes
Ctrl-b t	Show a clock
Ctrl-b m	Mark the current pane
Ctrl-b '	Prompt for an index to switch to
Ctrl-b !	Break the current pane into a new window
Ctrl-b s	List all sessions
Ctrl-b :	Enter the tmux command prompt
Ctrl-b [	Enter copy mode (scrollback buffer)
Ctrl-b ]	Paste the buffer
Ctrl-b -	Split the window vertically
Ctrl-b =	Split the window horizontally
Ctrl-b f	Find window by text
Ctrl-b r	Reload tmux configuration

Command	Description
ssh user@host	Connect to a remote host
ssh -p port user@host	Connect to a remote host on a specific port
ssh -i keyfile user@host	Connect using a specific private key file
ssh-copy-id user@host	Copy your public key to a remote host
ssh-keygen -t rsa -b 4096	Generate a new RSA key pair
ssh-add keyfile	Add a private key to the SSH agent
ssh-agent bash	Start the SSH agent
scp source user@host:destination	Copy files to a remote host
scp user@host:source destination	Copy files from a remote host
rsync -avz source user@host:destination	Sync files to a remote host
rsync -avz user@host:source destination	Sync files from a remote host
ssh user@host command	Execute a command on a remote host
ssh -L local_port:remote_host:remote_port user@host	Create an SSH tunnel (local forwarding)
ssh -R remote_port:local_host:local_port user@host	Create an SSH tunnel (remote forwarding)
ssh -D local_port user@host	Create a dynamic SOCKS proxy
~.	Terminate the SSH session
~C	Open command line interface during an SSH session
~&	Background the SSH session
ssh -X user@host	Enable X11 forwarding
ssh -v user@host	Verbose mode (debugging)
ssh -vv user@host	More verbose mode
ssh -q user@host	Quiet mode (suppress warnings)
ssh -f user@host command	Run SSH in the background
ssh -N user@host	Do not execute a remote command
ssh -o option=value user@host	Set an option for the SSH connection
ssh -c cipher user@host	Specify the cipher to use
ssh-keyscan host	Retrieve SSH public keys from a host
sshfs user@host:remote_dir local_dir	Mount a remote directory over SSH

Command	Description
git init	Initialize a new Git repository
git clone repository_url	Clone an existing repository
git status	Show the status of the working directory
git add file	Stage changes for commit
git commit -m "message"	Commit staged changes with a message
git push origin branch	Push commits to the remote repository
git pull origin branch	Pull updates from the remote repository
git fetch	Fetch changes from the remote repository
git merge branch	Merge a branch into the current branch
git branch	List all branches
git branch branch_name	Create a new branch
git checkout branch_name	Switch to a different branch
git checkout -b branch_name	Create and switch to a new branch
git log	Show commit history
git log --oneline	Show commit history in a condensed form
git diff	Show changes between commits, commit and working tree, etc
git reset --hard commit	Reset the working directory and index to a specific commit
git revert commit	Revert a specific commit
git stash	Stash changes in a dirty working directory
git stash pop	Apply stashed changes
git remote -v	Show remote repositories
git remote add name url	Add a remote repository
git tag	List tags
git tag tag_name	Create a new tag
git rm file	Remove a file from the working directory and index
git mv old_name new_name	Rename or move a file
git blame file	Show what revision and author last modified each line
git show commit	Show various types of objects
git config --global user.name "name"	Set the global username
git config --global user.email "email"	Set the global email
git rebase branch	Reapply commits on top of another base tip
git cherry-pick commit	Apply changes from a specific commit
git bisect start	Start binary search to find the commit that introduced a bug
git archive --format zip --output file.zip HEAD	Create a zip archive of the current branch
git gc	Cleanup unnecessary files and optimize the local repository

Command	Description
systemctl start service	Start a service
systemctl stop service	Stop a service
systemctl restart service	Restart a service
systemctl reload service	Reload a service's configuration
systemctl enable service	Enable a service to start on boot
systemctl disable service	Disable a service from starting on boot
systemctl status service	Show the status of a service
systemctl is-active service	Check if a service is active
systemctl is-enabled service	Check if a service is enabled
systemctl list-units	List all loaded units
systemctl list-unit-files	List installed unit files
systemctl daemon-reload	Reload systemd manager configuration
journalctl -u service	View logs for a specific service
journalctl -f	Follow the system journal
systemctl mask service	Mask a service to prevent it from being started
systemctl unmask service	Unmask a service
systemctl set-default target	Set the default target (e.g., multi-user, graphical)
systemctl get-default	Get the current default target
systemctl isolate target	Change to a different target
systemctl show service	Show properties of a unit
systemctl cat service	Show the unit file of a service
systemctl edit service	Edit a unit file (creates an override file)
systemctl reset-failed service	Reset the failed state of a unit
systemctl poweroff	Power off the system
systemctl reboot	Reboot the system
systemctl suspend	Suspend the system
systemctl hibernate	Hibernate the system
systemctl hybrid-sleep	Hibernate and suspend the system
systemd-analyze blame	Show the time taken to initialize each service
systemd-analyze critical-chain	Show the critical chain of units
systemd-analyze plot > plot.svg	Generate a graphical representation of the boot process
timedatectl	Control the system time and date
hostnamectl	Control the system hostname
localectl	Control the system locale
loginctl	Control the system logind

Command	Description
docker ps	List running containers
docker ps -a	List all containers
docker images	List all images
docker pull image	Pull an image from a registry
docker run image	Run a container from an image
docker run -d image	Run a container in detached mode
docker run -it image	Run a container in interactive mode
docker stop container	Stop a running container
docker start container	Start a stopped container
docker restart container	Restart a container
docker rm container	Remove a container
docker rmi image	Remove an image
docker exec -it container bash	Execute a command in a running container
docker logs container	View logs of a container
docker build -t image .	Build an image from a Dockerfile
docker-compose up	Start containers defined in docker-compose.yml
docker-compose down	Stop and remove containers defined in docker-compose.yml
docker network ls	List all networks
docker network create network	Create a new network
docker volume ls	List all volumes
docker volume create volume	Create a new volume
docker inspect container	Display detailed information on a container
docker tag source_image target_image	Tag an image
docker push image	Push an image to a registry
docker pull image	Pull an image from a registry
docker save -o image.tar image	Save an image to a tar file
docker load -i image.tar	Load an image from a tar file
docker stats container	Display resource usage statistics of a container
docker top container	Display the running processes of a container
docker cp source_path container:dest_path	Copy files/folders between a container and the local filesystem
docker update --cpus=2 container	Update resource limits of a container
docker history image	Show the history of an image
docker diff container	Inspect changes to files or directories on a container’s filesystem
docker export container -o container.tar	Export a container’s filesystem to a tar archive
docker import file.tar	Import a tarball to create a filesystem image

Command	Description
kubectl get nodes	List all nodes
kubectl get pods	List all pods in the default namespace
kubectl get pods -n namespace	List all pods in a specific namespace
kubectl get services	List all services in the default namespace
kubectl describe pod pod_name	Show detailed information about a specific pod
kubectl logs pod_name	Print the logs of a specific pod
kubectl exec -it pod_name -- bash	Execute a command in a running pod
kubectl apply -f file.yaml	Apply a configuration file
kubectl create -f file.yaml	Create resources from a configuration file
kubectl delete -f file.yaml	Delete resources defined in a configuration file
kubectl scale --replicas=3 deployment/app	Scale a deployment to 3 replicas
kubectl rollout status deployment/app	Check the rollout status of a deployment
kubectl rollout undo deployment/app	Roll back a deployment
kubectl expose deployment app --type=LoadBalancer --port=80	Expose a deployment as a service
kubectl port-forward pod_name 8080:80	Forward a local port to a port on a pod
kubectl get namespaces	List all namespaces
kubectl create namespace namespace	Create a new namespace
kubectl config set-context --current --namespace=namespace	Set the current namespace
kubectl get events	List all events
kubectl get secrets	List all secrets in the default namespace
kubectl get configmaps	List all configmaps in the default namespace
kubectl describe node node_name	Show detailed information about a specific node
kubectl get deployment	List all deployments in the default namespace
kubectl describe service service_name	Show detailed information about a specific service
kubectl set image deployment/app app=nginx:1.16	Update the image of a deployment
kubectl edit deployment app	Edit a resource on the server
kubectl delete pod pod_name	Delete a specific pod
kubectl delete service service_name	Delete a specific service
kubectl apply -f https://k8s.io/examples/application/deployment.yaml	Apply a deployment from a URL
kubectl get pvc	List all persistent volume claims
kubectl get pv	List all persistent volumes
kubectl cordon node_name	Mark a node as unschedulable
kubectl drain node_name	Drain a node by evicting all pods
kubectl taint nodes node_name key=value:NoSchedule	Taint a node to prevent scheduling

Command	Description
ansible all -m ping	Ping all hosts
ansible-playbook playbook.yaml	Run a playbook
ansible all -a "command"	Run a command on all hosts
ansible all -m setup	Gather facts from all hosts
ansible all -m yum -a "name=package state=present"	Install a package using yum
ansible all -m copy -a "src=/local/path dest=/remote/path"	Copy files to remote hosts
ansible-vault create secret.yaml	Create an encrypted file
ansible-vault edit secret.yaml	Edit an encrypted file
ansible-vault decrypt secret.yaml	Decrypt an encrypted file
ansible-playbook --ask-vault-password playbook.yaml	Run a playbook with vault password
ansible-galaxy install role_name	Install a role from Ansible Galaxy
ansible-galaxy list	List installed roles
ansible-doc -l	List all modules
ansible-doc module_name	Show documentation for a specific module
ansible-playbook -i inventory playbook.yaml	Run a playbook with a specific inventory
ansible all -m service -a "name=service state=started"	Manage services on remote hosts
ansible all -m file -a "path=/remote/path state=directory"	Ensure a directory exists on remote hosts
ansible all -m user -a "name=username state=present"	Ensure a user exists on remote hosts
ansible-playbook --check playbook.yaml	Run a playbook in check mode
ansible-playbook --diff playbook.yaml	Show changes made by the playbook
ansible-playbook -e "variable=value" playbook.yaml	Pass extra variables to the playbook
ansible-playbook --tags "tag_name" playbook.yaml	Run playbook tasks with specific tags
ansible-inventory --list -i inventory	List inventory hosts
ansible-inventory --graph -i inventory	Show inventory graph
ansible-config dump	Dump the Ansible configuration
ansible-config list	List all Ansible configuration options
ansible-pull -U repo_url	Pull and run a playbook from a remote Git repository
ansible-playbook --limit "host_pattern" playbook.yaml	Limit playbook run to specific hosts
ansible-playbook --start-at-task "task_name" playbook.yaml	Start playbook run at a specific task
ansible-galaxy init role_name	Initialize a new role

Command	Description
iptables -L	List all rules
iptables -A chain -j target	Append a rule to a chain
iptables -I chain rule_num -j target	Insert a rule at a specific position in a chain
iptables -D chain rule_num	Delete a rule from a chain by number
iptables -F	Flush all rules
iptables -X	Delete all user-defined chains
iptables -P chain target	Set the default policy for a chain
iptables -N chain	Create a new user-defined chain
iptables -A INPUT -p tcp --dport port -j ACCEPT	Allow incoming TCP traffic on a specific port
iptables -A OUTPUT -p tcp --sport port -j ACCEPT	Allow outgoing TCP traffic on a specific port
iptables -A FORWARD -i interface -j ACCEPT	Allow forwarding from a specific interface
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT	Allow established and related connections
iptables -A INPUT -s ip_address -j DROP	Block traffic from a specific IP address
iptables -A INPUT -p icmp -j ACCEPT	Allow ICMP (ping) traffic
iptables -A INPUT -p udp --dport port -j ACCEPT	Allow incoming UDP traffic on a specific port
iptables -A INPUT -p tcp --dport 22 -j ACCEPT	Allow SSH traffic
iptables -A INPUT -j REJECT	Reject all other incoming traffic
iptables-save > /etc/iptables/rules.v4	Save the current rules to a file
iptables-restore < /etc/iptables/rules.v4	Restore rules from a file

Command	Description
nft list ruleset	List all rulesets
nft add table inet filter	Create a new table
nft add chain inet filter input { type filter hook input priority 0; }	Create a new chain
nft add rule inet filter input ip saddr ip_address drop	Drop traffic from a specific IP address
nft add rule inet filter input tcp dport port accept	Allow incoming TCP traffic on a specific port
nft add rule inet filter input udp dport port accept	Allow incoming UDP traffic on a specific port
nft add rule inet filter input icmp type echo-request accept	Allow ICMP (ping) traffic
nft add rule inet filter input ct state established,related accept	Allow established and related connections
nft add rule inet filter input iifname interface accept	Allow traffic from a specific interface
nft add rule inet filter output tcp sport port accept	Allow outgoing TCP traffic on a specific port
nft add rule inet filter forward iifname interface oifname interface accept	Allow forwarding between interfaces
nft delete rule inet filter input handle handle_number	Delete a specific rule by handle number
nft delete chain inet filter input	Delete a chain
nft delete table inet filter	Delete a table
nft -f /etc/nftables.conf	Load rules from a configuration file
nft save > /etc/nftables.conf	Save the current ruleset to a file
nft -i /etc/nftables.conf	Load rules from a file interactively
nft monitor	Monitor changes to the ruleset
nft add set inet filter blacklist { type ipv4_addr; }	Create an IP set
nft add element inet filter blacklist { ip_address }	Add an IP address to the set
nft delete element inet filter blacklist { ip_address }	Remove an IP address from the set
nft add rule inet filter input ip saddr @blacklist drop	Drop traffic from IP addresses in the set

Command	Description
crontab -e	Edit the current user's crontab
crontab -l	List the current user's crontab
crontab -r	Remove the current user's crontab
crontab -u user -e	Edit another user's crontab
crontab -u user -l	List another user's crontab
crontab -u user -r	Remove another user's crontab
@reboot command	Run once at startup
@yearly command	Run once a year (0 0 1 1 *)
@annually command	Run once a year (0 0 1 1 *)
@monthly command	Run once a month (0 0 1 * *)
@weekly command	Run once a week (0 0 * * 0)
@daily command	Run once a day (0 0 * * *)
@midnight command	Run once a day (0 0 * * *)
@hourly command	Run once an hour (0 * * * *)
* * * * * command	Run every minute
*/5 * * * * command	Run every 5 minutes
0 * * * * command	Run at the beginning of every hour
0 0 * * * command	Run at midnight every day
0 0 1 * * command	Run at midnight on the first of every month
0 0 1 1 * command	Run at midnight on January 1st
0 9 * * 1-5 command	Run at 9 AM on weekdays
0 22 * * 1-5 command	Run at 10 PM on weekdays
MAILTO="email@example.com"	Send cron job output to the specified email address
0 0 * * * /path/to/script.sh	Run a script daily at midnight
0 5 * * * /path/to/backup.sh	Run a backup script daily at 5 AM
*/10 * * * * /path/to/check.sh	Run a script every 10 minutes
0 0 * * 0 /path/to/weekly.sh	Run a script weekly on Sundays at midnight
0 0 1 * * /path/to/monthly.sh	Run a script monthly on the first day at midnight
0 0 1 1 * /path/to/yearly.sh	Run a script yearly on January 1st at midnight

Command	Description
awk '{print}' file	Print all lines in a file
awk '{print $1}' file	Print the first field of each line
awk '{print $1, $2}' file	Print the first and second fields of each line
awk '/pattern/ {print}' file	Print lines matching a pattern
awk 'NR==line_number' file	Print a specific line number
awk 'NR==start, NR==end' file	Print a range of lines
awk '{sum += $1} END {print sum}' file	Sum the first field of all lines
awk 'BEGIN {print "Header"} {print} END {print "Footer"}' file	Add a header and footer to the output
awk -F, '{print $1}' file	Specify a field separator (comma in this case)
awk '{if ($1 > 10) print}' file	Print lines where the first field is greater than 10
awk '{gsub(/old/, "new"); print}' file	Replace all occurrences of "old" with "new"
awk '{print NR, $0}' file	Print line numbers with output
awk '{print length($0)}' file	Print the length of each line
awk '{print $NF}' file	Print the last field of each line
awk '{print $(NF-1)}' file	Print the second to last field of each line
awk '{count[$1]++} END {for (word in count) print word, count[word]}' file	Count occurrences of each word in the first field
awk 'NR % 2 == 0 {print}' file	Print every second line
awk '{print toupper($0)}' file	Convert text to uppercase
awk '{print tolower($0)}' file	Convert text to lowercase
awk 'BEGIN {FS=":"; OFS="-"} {print $1, $2}' file	Change input and output field separators

Command	Description
sed 's/old/new/' file	Replace the first occurrence of "old" with "new"
sed 's/old/new/g' file	Replace all occurrences of "old" with "new"
sed -i 's/old/new/g' file	Replace all occurrences in the file (in-place)
sed 's/old/new/2' file	Replace the second occurrence of "old" with "new"
sed 's/old/new/gi' file	Replace all occurrences, case insensitive
sed '1,3s/old/new/' file	Replace occurrences between lines 1 and 3
sed '3s/old/new/' file	Replace occurrences on the third line
sed '/pattern/s/old/new/' file	Replace occurrences on lines matching a pattern
sed 's/^/prefix/' file	Add a prefix to each line
sed 's/$/suffix/' file	Add a suffix to each line
sed '/pattern/d' file	Delete lines matching a pattern
sed '3d' file	Delete the third line
sed '1,3d' file	Delete lines 1 through 3
sed '$d' file	Delete the last line
sed -n '2,4p' file	Print lines 2 through 4
sed -n '/pattern/p' file	Print lines matching a pattern
sed -e 'command1' -e 'command2' file	Apply multiple commands
sed 's/.*\(pattern\).*/\1/' file	Extract and print a pattern
sed 'y/abc/ABC/' file	Translate characters
sed -i.bak 's/old/new/g' file	Replace all occurrences and create a backup file
sed '10q' file	Quit after 10 lines
sed 's/\([0-9]\{3\}\)-\([0-9]\{2\}\)-\([0-9]\{4\}\)/\1\2\3/' file	Remove dashes from SSN format
sed 's/ *$//' file	Remove trailing whitespace
sed 's/[^[:alnum:]]//g' file	Remove all non-alphanumeric characters

Command	Description
grep "pattern" file	Search for a pattern in a file
grep -i "pattern" file	Case-insensitive search
grep -v "pattern" file	Invert match, show lines that do not match
grep -r "pattern" directory	Recursively search in a directory
grep -l "pattern" file	Show file names containing the pattern
grep -c "pattern" file	Count occurrences of the pattern
grep -n "pattern" file	Show line numbers of matches
grep -w "pattern" file	Match whole words only
grep -A num "pattern" file	Show num lines after match
grep -B num "pattern" file	Show num lines before match
grep -C num "pattern" file	Show num lines around match
grep -e "pattern1" -e "pattern2" file	Search for multiple patterns
grep --exclude=*.txt "pattern" *	Exclude files matching a pattern
grep --include=*.txt "pattern" *	Include only files matching a pattern
grep -f patternfile file	Use patterns from a file
grep -q "pattern" file	Quiet mode, return 0 if pattern is found
grep --color=auto "pattern" file	Highlight matches in color
grep -o "pattern" file	Print only matching parts of a line
grep --line-buffered "pattern" file	Use line buffering (useful for streaming)

Command	Description
find . -name "filename"	Find files by name
find . -iname "filename"	Find files by name (case-insensitive)
find . -type d -name "dirname"	Find directories by name
find . -type f -name "filename"	Find regular files by name
find . -size +1M	Find files larger than 1MB
find . -size -1M	Find files smaller than 1MB
find . -mtime -1	Find files modified in the last day
find . -atime -1	Find files accessed in the last day
find . -user username	Find files owned by a specific user
find . -group groupname	Find files owned by a specific group
find . -perm 644	Find files with specific permissions
find . -exec command {} \;	Execute a command on each file found
find . -exec rm {} \;	Delete all files found
find . -print	Print the full file names
find . -maxdepth 1 -name "filename"	Find files in the current directory only
find . -mindepth 2 -name "filename"	Find files not in the top-level directory
find . -type l	Find symbolic links
find . -type l -xtype f	Find broken symbolic links
find . -empty	Find empty files and directories
find . -newer file	Find files newer than a specific file
find . -name "*.txt" -or -name "*.md"	Find files matching multiple patterns
find . -path "./dir/*" -prune -o -name "*.txt" -print	Exclude a directory and find files
find . -ctime +10	Find files changed more than 10 days ago
find . -cmin -60	Find files changed in the last 60 minutes
find / -type f 2>/dev/null	Find all files on the system, ignoring permission errors

Command	Description
screen	Start a new screen session
screen -S session_name	Start a new session named session_name
screen -ls	List all screen sessions
screen -r session_name	Resume a detached session named session_name
screen -d -r session_name	Detach and reattach to session_name
screen -X -S session_name quit	Kill a session named session_name
Ctrl-a d	Detach from the current session
Ctrl-a c	Create a new window
Ctrl-a "	List all windows
Ctrl-a 0	Switch to window 0
Ctrl-a A	Rename the current window
Ctrl-a n	Switch to the next window
Ctrl-a p	Switch to the previous window
Ctrl-a k	Kill the current window
Ctrl-a Ctrl-a	Switch between the current and previous window
Ctrl-a S	Split the screen horizontally
Ctrl-a \|	Split the screen vertically
Ctrl-a tab	Switch to the next region
Ctrl-a X	Close the current region
Ctrl-a Q	Close all regions except the current one
Ctrl-a space	Toggle between layouts
Ctrl-a :resize	Resize the current region
Ctrl-a :fit	Fit the current region to the screen
Ctrl-a [	Enter copy mode
Ctrl-a ]	Paste copied text
Ctrl-a ?	Show key bindings help
Ctrl-a H	Begin/end logging of the session
Ctrl-a _	Lock the terminal
Ctrl-a m	Monitor the current window for activity
Ctrl-a M	Monitor the current window for silence
Ctrl-a D D	Detach and logout from the session

Command	Description
rsync -av source destination	Archive mode, verbose
rsync -avz source destination	Archive mode, compress during transfer
rsync -av --progress source destination	Show progress during transfer
rsync -av --delete source destination	Delete extraneous files from destination
rsync -av --exclude='pattern' source destination	Exclude files matching a pattern
rsync -av --include='pattern' source destination	Include only files matching a pattern
rsync -av -e ssh source user@host:destination	Use SSH as the transport
rsync -av --dry-run source destination	Perform a trial run with no changes made
rsync -av --partial source destination	Keep partially transferred files
rsync -av --bwlimit=KBps source destination	Limit bandwidth during transfer
rsync -av --size-only source destination	Skip files that match in size
rsync -av --checksum source destination	Skip files that match in checksum
rsync -av --times source destination	Preserve modification times
rsync -av --perms source destination	Preserve permissions
rsync -av --owner source destination	Preserve owner
rsync -av --group source destination	Preserve group
rsync -av --links source destination	Copy symlinks as symlinks
rsync -av --hard-links source destination	Preserve hard links
rsync -av --copy-links source destination	Copy symlinks as files
rsync -av --copy-dirlinks source destination	Transform symlinks to directories into real dirs
rsync -av --no-links source destination	Skip copying symlinks
rsync -av --safe-links source destination	Ignore symlinks that point outside source tree
rsync -av --delete-excluded source destination	Delete excluded files from destination
rsync -av --max-size=SIZE source destination	Limit maximum size of files to transfer
rsync -av --min-size=SIZE source destination	Limit minimum size of files to transfer
rsync -av --backup source destination	Backup files that are replaced
rsync -av --backup-dir=DIR source destination	Backup files into a specific directory
rsync -av --suffix=SUFFIX source destination	Define suffix for backup files
rsync -av --inplace source destination	Update destination files in place
rsync -av --append source destination	Append data onto shorter files
rsync -av --append-verify source destination	Append and verify full file content
rsync -av --ignore-existing source destination	Skip updating files that already exist
rsync -av --remove-source-files source destination	Remove source files after transfer

Command	Description
tar -cvf archive.tar file_or_directory	Create a tar archive
tar -xvf archive.tar	Extract a tar archive
tar -tvf archive.tar	List contents of a tar archive
tar -cvzf archive.tar.gz file_or_directory	Create a gzip-compressed tar archive
tar -xvzf archive.tar.gz	Extract a gzip-compressed tar archive
tar -cvjf archive.tar.bz2 file_or_directory	Create a bzip2-compressed tar archive
tar -xvjf archive.tar.bz2	Extract a bzip2-compressed tar archive
tar -cvJf archive.tar.xz file_or_directory	Create a xz-compressed tar archive
tar -xvJf archive.tar.xz	Extract a xz-compressed tar archive
tar -cvf - file_or_directory \| ssh user@host "tar -xvf - -C /destination"	Copy files over SSH
tar -rf archive.tar file	Append files to an existing tar archive
tar -uf archive.tar file	Update files in an existing tar archive
tar -cvf archive.tar --exclude="*.txt" file_or_directory	Create tar archive excluding certain files
tar -cvf archive.tar --exclude-vcs file_or_directory	Create tar archive excluding version control files
tar --delete -f archive.tar file	Delete files from a tar archive
tar -cvf archive.tar -T filelist.txt	Create tar archive from a list of files
tar -xvf archive.tar -C /destination	Extract tar archive to a specific directory
tar --strip-components=number -xvf archive.tar	Extract tar archive, removing a number of leading components
tar --transform='s/old/new/' -cvf archive.tar file_or_directory	Create tar archive with transformed file names
tar -xzvf archive.tar.gz --wildcards '*.txt'	Extract specific files from a compressed tar archive

Command	Description
gzip file	Compress a file
gzip -d file.gz	Decompress a file
gzip -k file	Compress a file, keeping the original
gzip -r directory	Recursively compress files in a directory
gzip -l file.gz	List compressed file details
gzip -t file.gz	Test compressed file integrity
gzip -v file	Compress a file with verbose output
gzip -1 file	Compress a file with fastest speed
gzip -9 file	Compress a file with best compression
zcat file.gz	View contents of a compressed file
zgrep "pattern" file.gz	Search for a pattern in a compressed file
zless file.gz	View a compressed file with less
zcmp file1.gz file2.gz	Compare compressed files
zdiff file1.gz file2.gz	Show differences between compressed files

Command	Description
bzip2 file	Compress a file
bzip2 -d file.bz2	Decompress a file
bzip2 -k file	Compress a file, keeping the original
bzip2 -z file	Compress a file
bzip2 -t file.bz2	Test compressed file integrity
bzip2 -c file > file.bz2	Compress a file to standard output
bzip2 -f file	Force compression or decompression
bzip2 -v file	Compress a file with verbose output
bzip2 -1 file	Compress a file with fastest speed
bzip2 -9 file	Compress a file with best compression
bzcat file.bz2	View contents of a compressed file
bzgrep "pattern" file.bz2	Search for a pattern in a compressed file
bzless file.bz2	View a compressed file with less
bzcmp file1.bz2 file2.bz2	Compare compressed files
bzdiff file1.bz2 file2.bz2	Show differences between compressed files

Command	Description
curl url	Fetch the content of a URL
curl -o file url	Save the content to a file
curl -O url	Save the content to a file with the same name
curl -L url	Follow redirects
curl -I url	Fetch headers only
curl -d "data" url	Send data with a POST request
curl -X POST url	Send a POST request
curl -X PUT url	Send a PUT request
curl -X DELETE url	Send a DELETE request
curl -H "Header: value" url	Send a custom header
curl -u user:password url	Send basic authentication
curl -F "name=value" url	Send a multipart form data
curl -k url	Allow insecure SSL connections
curl --cert certfile url	Send a client certificate
curl -b "name=value" url	Send cookies
curl -c cookiefile url	Save cookies to a file
curl --limit-rate 100k url	Limit the transfer rate
curl --compressed url	Request a compressed response
curl --retry num url	Retry a request on failure
curl --silent url	Silent mode (suppress output)
curl --progress-bar url	Display a progress bar
curl --http2 url	Use HTTP/2 protocol
curl --interface interface url	Use a specific network interface
curl --ipv4 url	Use IPv4 only
curl --ipv6 url	Use IPv6 only
curl --location-trusted url	Follow redirects and send authentication to other hosts
curl --data-urlencode "name=value" url	URL encode data
curl --max-time seconds url	Set a maximum time for the request
curl --connect-timeout seconds url	Set a maximum time for the connection
curl --proxy proxy_url url	Use a proxy server

Command	Description
wget url	Download a file
wget -O file url	Save the download with a specific name
wget -P /path url	Save the download to a specific directory
wget -c url	Continue a partially downloaded file
wget -b url	Download in the background
wget -i file	Download URLs listed in a file
wget -r url	Download recursively
wget -l depth url	Set the download depth
wget -k url	Convert links to be suitable for local viewing
wget -m url	Mirror a website
wget -p url	Download all necessary files to display a webpage
wget --limit-rate=100k url	Limit the download speed
wget --user=user --password=password url	Download with basic authentication
wget --header="Header: value" url	Send a custom header
wget --no-check-certificate url	Ignore SSL certificate errors
wget --quiet url	Quiet mode (no output)
wget --show-progress url	Show a progress bar
wget --spider url	Check if a URL exists
wget --no-clobber url	Do not overwrite existing files
wget --timestamping url	Download only if the remote file is newer than the local file
wget --directory-prefix=prefix url	Save files to a specific directory
wget --tries=num url	Set the number of retries
wget --wait=seconds url	Wait between downloads
wget --random-wait url	Wait a random amount of time between downloads
wget --delete-after url	Delete files after downloading
wget --mirror url	Mirror a website
wget --recursive url	Download files recursively
wget --level=depth url	Set the recursion depth
wget --user-agent="User-Agent" url	Set the user agent

Command	Description
mysql -u user -p	Connect to the MySQL server
CREATE DATABASE dbname;	Create a new database
DROP DATABASE dbname;	Delete a database
USE dbname;	Select a database
SHOW DATABASES;	List all databases
SHOW TABLES;	List all tables in the selected database
DESCRIBE tablename;	Show table structure
CREATE TABLE tablename (columns);	Create a new table
DROP TABLE tablename;	Delete a table
INSERT INTO tablename (columns) VALUES (values);	Insert data into a table
SELECT * FROM tablename;	Retrieve all data from a table
UPDATE tablename SET column=value WHERE condition;	Update data in a table
DELETE FROM tablename WHERE condition;	Delete data from a table
GRANT ALL PRIVILEGES ON dbname.* TO 'user'@'host' IDENTIFIED BY 'password';	Grant privileges to a user
FLUSH PRIVILEGES;	Reload privileges
SHOW GRANTS FOR 'user'@'host';	Show granted privileges
REVOKE ALL PRIVILEGES ON dbname.* FROM 'user'@'host';	Revoke privileges from a user
CREATE USER 'user'@'host' IDENTIFIED BY 'password';	Create a new user
DROP USER 'user'@'host';	Delete a user
SHOW PROCESSLIST;	Show running processes
EXIT;	Exit the MySQL shell
mysqldump -u user -p dbname > backup.sql	Backup a database
mysql -u user -p dbname < backup.sql	Restore a database
SHOW STATUS;	Show server status
SHOW VARIABLES;	Show server variables
SHOW INDEX FROM tablename;	Show indexes in a table
SHOW CREATE TABLE tablename;	Show the CREATE TABLE statement for a table
ALTER TABLE tablename ADD columnname datatype;	Add a column to a table
ALTER TABLE tablename DROP columnname;	Drop a column from a table
ALTER TABLE tablename MODIFY columnname datatype;	Modify a column in a table
ALTER TABLE tablename RENAME TO newtablename;	Rename a table
CREATE INDEX indexname ON tablename (columns);	Create an index on a table
DROP INDEX indexname ON tablename;	Drop an index from a table
SET GLOBAL max_connections = value;	Set a global variable
SHOW ENGINE INNODB STATUS;	Show InnoDB status

Command	Description
psql -U user -d dbname	Connect to the PostgreSQL server
CREATE DATABASE dbname;	Create a new database
DROP DATABASE dbname;	Delete a database
\c dbname	Connect to a database
\l	List all databases
\dt	List all tables in the connected database
\d tablename	Show table structure
CREATE TABLE tablename (columns);	Create a new table
DROP TABLE tablename;	Delete a table
INSERT INTO tablename (columns) VALUES (values);	Insert data into a table
SELECT * FROM tablename;	Retrieve all data from a table
UPDATE tablename SET column=value WHERE condition;	Update data in a table
DELETE FROM tablename WHERE condition;	Delete data from a table
GRANT ALL PRIVILEGES ON DATABASE dbname TO user;	Grant privileges to a user
REVOKE ALL PRIVILEGES ON DATABASE dbname FROM user;	Revoke privileges from a user
CREATE USER username WITH PASSWORD 'password';	Create a new user
DROP USER username;	Delete a user
\q	Exit the PostgreSQL shell
pg_dump -U user -d dbname -f backup.sql	Backup a database
psql -U user -d dbname -f backup.sql	Restore a database
\conninfo	Show connection information
\du	List all roles
\di	List all indexes
\df	List all functions
\dn	List all schemas
\dp	List table, view, and sequence access privileges
ALTER TABLE tablename ADD columnname datatype;	Add a column to a table
ALTER TABLE tablename DROP columnname;	Drop a column from a table
ALTER TABLE tablename ALTER COLUMN columnname TYPE datatype;	Modify a column in a table
ALTER TABLE tablename RENAME TO newtablename;	Rename a table
CREATE INDEX indexname ON tablename (columns);	Create an index on a table
DROP INDEX indexname;	Drop an index
VACUUM	Clean up and optimize the database
VACUUM FULL	Clean up and optimize the database (full)
ANALYZE	Collect statistics about the database
EXPLAIN SELECT * FROM tablename;	Show the execution plan for a query
SET search_path TO schema;	Set the search path to a specific schema

Command	Description
sudo systemctl start nginx	Start Nginx
sudo systemctl stop nginx	Stop Nginx
sudo systemctl restart nginx	Restart Nginx
sudo systemctl reload nginx	Reload Nginx configuration
sudo systemctl enable nginx	Enable Nginx to start on boot
sudo systemctl disable nginx	Disable Nginx from starting on boot
nginx -t	Test Nginx configuration
nginx -s reload	Reload Nginx configuration
nginx -s reopen	Reopen log files
nginx -s stop	Stop Nginx
nginx -s quit	Gracefully stop Nginx
/etc/nginx/nginx.conf	Main Nginx configuration file
/etc/nginx/sites-available/	Directory for available site configurations
/etc/nginx/sites-enabled/	Directory for enabled site configurations
sudo ln -s /etc/nginx/sites-available/site /etc/nginx/sites-enabled/	Enable a site configuration
sudo unlink /etc/nginx/sites-enabled/site	Disable a site configuration
server { ... }	Define a virtual server block
location / { ... }	Define a location block
listen 80;	Listen on port 80
listen 443 ssl;	Listen on port 443 with SSL
server_name domain.com;	Define the server name
root /var/www/html;	Define the document root
index index.html;	Define the default index file
error_page 404 /404.html;	Define a custom error page
access_log /var/log/nginx/access.log;	Define the access log file
error_log /var/log/nginx/error.log;	Define the error log file
proxy_pass http://backend;	Proxy requests to a backend server
rewrite ^/old/(.*)$ /new/$1 permanent;	Rewrite URL
location ~ \.php$ { ... }	Define a location block for PHP files
include /etc/nginx/conf.d/*.conf;	Include additional configuration files
ssl_certificate /etc/nginx/ssl/nginx.crt;	Define the SSL certificate
ssl_certificate_key /etc/nginx/ssl/nginx.key;	Define the SSL certificate key
ssl_protocols TLSv1.2 TLSv1.3;	Define the supported SSL protocols
ssl_ciphers HIGH:!aNULL:!MD5;	Define the supported SSL ciphers

Command	Description
sudo systemctl start apache2	Start Apache
sudo systemctl stop apache2	Stop Apache
sudo systemctl restart apache2	Restart Apache
sudo systemctl reload apache2	Reload Apache configuration
sudo systemctl enable apache2	Enable Apache to start on boot
sudo systemctl disable apache2	Disable Apache from starting on boot
apachectl configtest	Test Apache configuration
apachectl graceful	Gracefully restart Apache
/etc/apache2/apache2.conf	Main Apache configuration file
/etc/apache2/sites-available/	Directory for available site configurations
/etc/apache2/sites-enabled/	Directory for enabled site configurations
sudo a2ensite site	Enable a site configuration
sudo a2dissite site	Disable a site configuration
sudo a2enmod module	Enable a module
sudo a2dismod module	Disable a module
sudo a2enconf config	Enable a configuration
sudo a2disconf config	Disable a configuration
<VirtualHost *:80> ... </VirtualHost>	Define a virtual host for HTTP
<VirtualHost *:443> ... </VirtualHost>	Define a virtual host for HTTPS
ServerName domain.com	Define the server name
DocumentRoot /var/www/html	Define the document root
DirectoryIndex index.html	Define the default index file
ErrorLog /var/log/apache2/error.log	Define the error log file
CustomLog /var/log/apache2/access.log combined	Define the access log file
SSLEngine on	Enable SSL
SSLCertificateFile /etc/apache2/ssl/apache.crt	Define the SSL certificate
SSLCertificateKeyFile /etc/apache2/ssl/apache.key	Define the SSL certificate key
SSLProtocol all -SSLv2 -SSLv3	Define the supported SSL protocols
SSLCipherSuite HIGH:!aNULL:!MD5	Define the supported SSL ciphers
ProxyPass /app http://backend/app	Proxy requests to a backend server
ProxyPassReverse /app http://backend/app	Adjust the URL in the Location header
RewriteEngine on	Enable URL rewriting
RewriteRule ^/old/(.*)$ /new/$1 [R=301,L]	Rewrite URL
<Directory /var/www/html> ... </Directory>	Define directory-specific settings
Options Indexes FollowSymLinks	Set directory options
AllowOverride All	Allow .htaccess to override settings
Require all granted	Allow access to a directory
Redirect permanent /old /new	Redirect a URL

Command	Description
firewall-cmd --state	Check the state of firewalld
firewall-cmd --reload	Reload firewalld configuration
firewall-cmd --get-active-zones	List all active zones
firewall-cmd --get-default-zone	Get the default zone
firewall-cmd --zone=zone --list-all	List all settings in a zone
firewall-cmd --zone=zone --add-source=source	Add a source to a zone
firewall-cmd --zone=zone --add-port=port/protocol	Add a port to a zone
firewall-cmd --zone=zone --remove-port=port/protocol	Remove a port from a zone
firewall-cmd --zone=zone --add-service=service	Add a service to a zone
firewall-cmd --zone=zone --remove-service=service	Remove a service from a zone
firewall-cmd --permanent	Apply changes permanently
firewall-cmd --runtime-to-permanent	Save runtime changes to permanent configuration
firewall-cmd --add-masquerade	Enable masquerading (NAT)
firewall-cmd --remove-masquerade	Disable masquerading (NAT)
firewall-cmd --zone=zone --add-rich-rule='rule'	Add a rich rule to a zone
firewall-cmd --zone=zone --remove-rich-rule='rule'	Remove a rich rule from a zone

Command	Description
sudo ufw enable	Enable UFW
sudo ufw disable	Disable UFW
sudo ufw status	Show the current status of UFW and list rules
sudo ufw status verbose	Show the current status of UFW with detailed information
sudo ufw allow port	Allow incoming traffic on a specific port
sudo ufw allow from IP	Allow incoming traffic from a specific IP address
sudo ufw allow from IP to any port port	Allow incoming traffic from a specific IP to a specific port
sudo ufw allow proto tcp from IP to any port port	Allow incoming TCP traffic from a specific IP to a specific port
sudo ufw deny port	Deny incoming traffic on a specific port
sudo ufw deny from IP	Deny incoming traffic from a specific IP address
sudo ufw deny from IP to any port port	Deny incoming traffic from a specific IP to a specific port
sudo ufw delete allow port	Delete an allow rule for a specific port
sudo ufw delete deny port	Delete a deny rule for a specific port
sudo ufw default allow outgoing	Set the default policy to allow outgoing traffic
sudo ufw default deny outgoing	Set the default policy to deny outgoing traffic
sudo ufw default allow incoming	Set the default policy to allow incoming traffic
sudo ufw default deny incoming	Set the default policy to deny incoming traffic
sudo ufw reset	Reset UFW rules to the default state
sudo ufw show raw	Show the raw iptables rules generated by UFW
sudo ufw logging on	Enable logging for UFW
sudo ufw logging off	Disable logging for UFW
sudo ufw logging low	Set logging level to low
sudo ufw logging medium	Set logging level to medium
sudo ufw logging high	Set logging level to high
sudo ufw app list	List all available application profiles
sudo ufw app info Application	Show information about a specific application profile
sudo ufw allow Application	Allow an application by profile
sudo ufw deny Application	Deny an application by profile
sudo ufw reload	Reload UFW to apply changes
sudo ufw route allow proto tcp from any to any port port	Allow routing for a specific port over TCP
sudo ufw route deny proto udp from any to any port port	Deny routing for a specific port over UDP

Command	Description
sestatus	Check the status of SELinux
getenforce	Get the current mode of SELinux
setenforce 0	Set SELinux to permissive mode
setenforce 1	Set SELinux to enforcing mode
semanage boolean -l	List all SELinux booleans
semanage boolean -m --on boolean_name	Enable an SELinux boolean
semanage boolean -m --off boolean_name	Disable an SELinux boolean
semanage fcontext -l	List all file context mappings
semanage fcontext -a -t type '/path(/.*)?'	Add a file context mapping
restorecon -Rv /path	Apply file context to files
chcon -t type /path	Change the file context
ls -Z	List files with SELinux context
ps -Z	List processes with SELinux context
grep AVC /var/log/audit/audit.log	Search for SELinux denials in the audit log
ausearch -m avc -ts recent	Search for recent SELinux denials
audit2allow -w -a	Display audit log entries that require policy changes
audit2allow -a -M mymodule	Generate a policy module to allow denials
semodule -i mymodule.pp	Install a policy module
semanage port -l	List all SELinux port mappings
semanage port -a -t type -p tcp port	Add a port mapping
semanage port -d -p tcp port	Delete a port mapping
semanage permissive -a type	Set a domain to permissive mode
semanage permissive -d type	Remove a domain from permissive mode
seinfo	Display SELinux policy information
semodule -l	List all installed policy modules
semodule -r module_name	Remove an installed policy module
sealert -a /var/log/audit/audit.log	Analyze audit log for SELinux denials

Command	Description
aa-status	Check the status of AppArmor
aa-enforce /etc/apparmor.d/profile	Set a profile to enforce mode
aa-complain /etc/apparmor.d/profile	Set a profile to complain mode
aa-logprof	Update profiles based on log events
aa-genprof /path/to/executable	Generate a new profile for an executable
aa-disable /etc/apparmor.d/profile	Disable a profile
aa-parse -r /etc/apparmor.d/profile	Reload a profile
apparmor_parser -r /etc/apparmor.d/profile	Reload a profile
apparmor_parser -R /etc/apparmor.d/profile	Remove a profile from the kernel
aa-unconfined	List unconfined processes
aa-notify	Display AppArmor notifications
aa-exec -p profile -- command	Execute a command under a specific profile
aa-audit /etc/apparmor.d/profile	Set a profile to audit mode
cat /var/log/syslog \| grep apparmor	Search for AppArmor messages in the syslog
grep "audit" /var/log/kern.log	Search for AppArmor audit messages in the kernel log
ls -lZ /path	List files with AppArmor context
aa-cleanprof	Remove unnecessary rules from a profile
aa-enforce /etc/apparmor.d/*	Set all profiles to enforce mode
aa-complain /etc/apparmor.d/*	Set all profiles to complain mode
journalctl -xe \| grep apparmor	Search for AppArmor events in the journal log
sudo apparmor_parser -r /etc/apparmor.d/usr.bin.program	Reload a specific AppArmor profile
sudo aa-genprof /path/to/program	Generate a new profile for a program
sudo aa-logprof /var/log/syslog	Update profiles based on log events
sudo aa-enforce /etc/apparmor.d/usr.bin.program	Enforce a specific AppArmor profile
sudo aa-complain /etc/apparmor.d/usr.bin.program	Set a specific AppArmor profile to complain mode

Command	Description
ldapsearch -x -b "base_dn" "(filter)"	Search for entries in the LDAP directory
ldapadd -x -D "bind_dn" -W -f file.ldif	Add entries to the LDAP directory
ldapdelete -x -D "bind_dn" -W "dn"	Delete entries from the LDAP directory
ldapmodify -x -D "bind_dn" -W -f file.ldif	Modify entries in the LDAP directory
ldapcompare -x -D "bind_dn" -W "dn" attribute:value	Compare attribute values
ldapwhoami -x -D "bind_dn" -W	Show the distinguished name of the authenticated user
ldapmodrdn -x -D "bind_dn" -W "dn" "new_rdn"	Modify the RDN of an entry
slapcat -v -l backup.ldif	Export the LDAP directory to an LDIF file
slapadd -v -l backup.ldif	Import an LDIF file into the LDAP directory
slapindex	Rebuild the LDAP directory indexes
slapd -d 1	Start the LDAP server in debug mode
ldapsearch -LLL -x -b "base_dn" "(filter)" attribute	Search and display specific attributes
ldapsearch -H ldap://ldap.example.com -x -b "base_dn" "(filter)"	Search using a specific LDAP URI
ldapsearch -ZZ -x -b "base_dn" "(filter)"	Search with StartTLS
ldapadd -ZZ -x -D "bind_dn" -W -f file.ldif	Add entries with StartTLS
ldapmodify -ZZ -x -D "bind_dn" -W -f file.ldif	Modify entries with StartTLS
ldapdelete -ZZ -x -D "bind_dn" -W "dn"	Delete entries with StartTLS
ldapwhoami -ZZ -x -D "bind_dn" -W	Show the distinguished name with StartTLS
ldapcompare -ZZ -x -D "bind_dn" -W "dn" attribute:value	Compare attribute values with StartTLS
ldapmodrdn -ZZ -x -D "bind_dn" -W "dn" "new_rdn"	Modify the RDN with StartTLS
ldapsearch -Y EXTERNAL -H ldapi:/// -b "cn=config"	Search the configuration directory
ldapadd -Y EXTERNAL -H ldapi:/// -f config.ldif	Add configuration entries
ldapmodify -Y EXTERNAL -H ldapi:/// -f config.ldif	Modify configuration entries
ldapdelete -Y EXTERNAL -H ldapi:/// "dn"	Delete configuration entries

Command	Description
pvcreate /dev/sdX	Create a physical volume
pvdisplay	Display information about physical volumes
pvscan	Scan all disks for physical volumes
vgcreate vgname /dev/sdX	Create a volume group
vgdisplay	Display information about volume groups
vgscan	Scan all disks for volume groups
vgextend vgname /dev/sdX	Add a physical volume to a volume group
vgreduce vgname /dev/sdX	Remove a physical volume from a volume group
lvcreate -L size -n lvname vgname	Create a logical volume
lvcreate -l 100%FREE -n lvname vgname	Create a logical volume using all free space
lvdisplay	Display information about logical volumes
lvextend -L+size /dev/vgname/lvname	Extend a logical volume by size
lvextend -l +100%FREE /dev/vgname/lvname	Extend a logical volume using all free space
lvreduce -L-size /dev/vgname/lvname	Reduce the size of a logical volume
lvremove /dev/vgname/lvname	Remove a logical volume
lvresize -L size /dev/vgname/lvname	Resize a logical volume
lvrename /dev/vgname/oldname newname	Rename a logical volume
vgremove vgname	Remove a volume group
pvremove /dev/sdX	Remove a physical volume
vgchange -a y vgname	Activate a volume group
vgchange -a n vgname	Deactivate a volume group
vgmerge vgname1 vgname2	Merge two volume groups
vgsplit vgname new_vgname /dev/sdX	Split a volume group into two
pvmove /dev/sdX	Move physical extents from one physical volume to another
vgcfgbackup	Backup volume group metadata
vgcfgrestore vgname	Restore volume group metadata
lvconvert --type raid1 --mirrors 1 /dev/vgname/lvname	Convert a logical volume to RAID1
lvchange -a y /dev/vgname/lvname	Activate a logical volume
lvchange -a n /dev/vgname/lvname	Deactivate a logical volume
lvscan	Scan for all logical volumes
vgextend vgname /dev/sdX	Add a physical volume to a volume group

Command	Description
zpool create pool /dev/sdX	Create a new storage pool
zpool destroy pool	Destroy a storage pool
zpool status	Show the status of all pools
zpool list	List all pools
zpool add pool /dev/sdX	Add a device to a pool
zpool remove pool /dev/sdX	Remove a device from a pool
zpool replace pool /dev/sdX /dev/sdY	Replace a device in a pool
zpool scrub pool	Scrub the data in a pool
zpool export pool	Export a pool
zpool import pool	Import a pool
zfs create pool/dataset	Create a new dataset
zfs destroy pool/dataset	Destroy a dataset
zfs list	List all datasets
zfs mount pool/dataset	Mount a dataset
zfs unmount pool/dataset	Unmount a dataset
zfs snapshot pool/dataset@snapshot	Create a snapshot of a dataset
zfs rollback pool/dataset@snapshot	Roll back to a snapshot
zfs send pool/dataset@snapshot	Send a snapshot
zfs receive pool/dataset	Receive a snapshot
zfs get property pool/dataset	Get a property value
zfs set property=value pool/dataset	Set a property value
zfs rename pool/dataset new_name	Rename a dataset
zfs clone pool/dataset@snapshot new_dataset	Clone a snapshot
zfs promote pool/dataset	Promote a clone to a full dataset
zfs diff pool/dataset@snapshot1 pool/dataset@snapshot2	Show differences between snapshots
zfs upgrade -a	Upgrade all ZFS filesystems
zpool upgrade -a	Upgrade all ZFS pools
zpool history pool	Show command history for a pool
zpool iostat pool	Show I/O statistics for a pool
zpool clear pool	Clear errors in a pool
zpool trim pool	Trim free space in a pool
zfs hold tag pool/dataset@snapshot	Hold a snapshot
zfs release tag pool/dataset@snapshot	Release a held snapshot
zfs inherit property pool/dataset	Inherit a property from the parent

Command	Description
mkfs.btrfs /dev/sdX	Create a Btrfs filesystem
btrfs filesystem show	Show Btrfs filesystems
btrfs filesystem df /mountpoint	Show disk usage of a Btrfs filesystem
btrfs filesystem balance /mountpoint	Balance a Btrfs filesystem
btrfs filesystem resize size /mountpoint	Resize a Btrfs filesystem
btrfs device add /dev/sdX /mountpoint	Add a device to a Btrfs filesystem
btrfs device delete /dev/sdX /mountpoint	Remove a device from a Btrfs filesystem
btrfs scrub start /mountpoint	Scrub a Btrfs filesystem
btrfs scrub status /mountpoint	Show scrub status
btrfs balance start /mountpoint	Start a balance operation
btrfs balance status /mountpoint	Show balance status
btrfs subvolume create /mountpoint/subvolume	Create a subvolume
btrfs subvolume delete /mountpoint/subvolume	Delete a subvolume
btrfs subvolume list /mountpoint	List all subvolumes
btrfs subvolume snapshot /mountpoint/subvolume /mountpoint/snapshot	Create a snapshot
btrfs send /mountpoint/subvolume	btrfs receive /mountpoint/snapshot`
btrfs subvolume set-default subvolid /mountpoint	Set the default subvolume
btrfs property set /mountpoint/subvolume ro true	Set a subvolume to read-only
btrfs property list /mountpoint/subvolume	List properties of a subvolume
btrfs quota enable /mountpoint	Enable quotas on a Btrfs filesystem
btrfs qgroup show /mountpoint	Show quota groups
btrfs qgroup limit size /mountpoint	Set a quota limit
btrfs rescue zero-log /dev/sdX	Repair a corrupted log
btrfs rescue chunk-recover /dev/sdX	Recover corrupted chunks
btrfs check /dev/sdX	Check a Btrfs filesystem
btrfs device scan	Scan for Btrfs devices
btrfs device stats /mountpoint	Show device statistics
btrfs filesystem defragment /mountpoint	Defragment a Btrfs filesystem
btrfs quota rescan -w /mountpoint	Rescan quotas
btrfs filesystem sync /mountpoint	Sync a Btrfs filesystem
btrfs replace start /dev/sdX /dev/sdY /mountpoint	Replace a device in a Btrfs filesystem
btrfs replace status /mountpoint	Show replace status

Command	Description
ping host	Check connectivity to a host
ping -c count host	Send a specific number of ping requests
ping -i interval host	Set the interval between ping requests
ping -t ttl host	Set the time-to-live for ping packets
traceroute host	Trace the route to a host
traceroute -m max_ttl host	Set the maximum TTL
traceroute -p port host	Set the destination port
traceroute -I host	Use ICMP echo instead of UDP
traceroute -T host	Use TCP SYN instead of UDP
mtr host	Network diagnostic tool combining ping and traceroute
mtr -r host	Run MTR in report mode
mtr -c count host	Set the number of pings in MTR
netstat -tuln	List all listening ports and services
netstat -i	Show network interfaces
netstat -rn	Show the routing table
netstat -s	Display network statistics
netstat -plnt	Show listening TCP ports
ss -tuln	List all listening ports and services (ss command)
ss -i	Show network interfaces (ss command)
ss -rn	Show the routing table (ss command)
ss -s	Display network statistics (ss command)
ss -plnt	Show listening TCP ports (ss command)
ip addr show	Display all IP addresses
ip link show	Show network interfaces
ip route show	Display the routing table
ip link set dev iface up	Bring an interface up
ip link set dev iface down	Bring an interface down
ifconfig	Display network interfaces
ifconfig iface up	Bring an interface up
ifconfig iface down	Bring an interface down
ifconfig iface inet addr	Assign an IP address to an interface
ifconfig iface hw ether MAC	Assign a MAC address to an interface
ethtool iface	Display Ethernet device settings
ethtool -s iface speed 1000 duplex full autoneg on	Set Ethernet device speed and duplex
tcpdump -i iface	Capture packets on an interface
tcpdump -n host host	Capture packets to/from a specific host
tcpdump -nn port port	Capture packets on a specific port
tcpdump -w file.pcap	Write packets to a file
tcpdump -r file.pcap	Read packets from a file
dig domain	DNS lookup for a domain
dig +short domain	Short DNS lookup for a domain
dig -x ip	Reverse DNS lookup
nslookup domain	DNS lookup for a domain (nslookup)
nslookup	Enter interactive mode (nslookup)
nslookup domain server	DNS lookup using a specific DNS server

Command	Description
dmesg	Display all messages from the kernel ring buffer
`dmesg	less`
`dmesg	grep pattern`
dmesg -c	Clear the ring buffer after printing
dmesg -T	Display human-readable timestamps for each message
dmesg -H	Enable colorized and human-readable output
dmesg -l level	Filter messages by log level (e.g., emerg, alert, crit, err, warn, notice, info, debug)
dmesg -n level	Set the log level of messages to print
dmesg -f facility	Filter messages by facility (e.g., kern, user, mail, daemon, auth, syslog, lpr, news, uucp, cron, authpriv, ftp, local0-local7)
dmesg -r	Raw output, no human-readable timestamps
dmesg --clear	Clear the kernel ring buffer
dmesg --level level	Set the log level for printing messages
dmesg --facility facility	Set the facility for printing messages
dmesg -w	Keep waiting for new messages and print them as they come
dmesg --follow	Alias for -w, keep waiting for new messages

Command	Description
journalctl	View the systemd journal
journalctl -b	Show messages from the current boot
journalctl -k	Show only kernel messages
journalctl -u service	Show messages for a specific service
journalctl -f	Follow new messages as they appear (similar to tail -f)
journalctl -r	Show messages in reverse chronological order
journalctl --since "time"	Show messages since a specific time
journalctl --until "time"	Show messages until a specific time
journalctl -p level	Show messages of a specific priority level (e.g., emerg, alert, crit, err, warn, notice, info, debug)
journalctl -xe	Show the last few log entries with details about system errors
journalctl --disk-usage	Show the disk space used by the journal
journalctl --vacuum-time=time	Remove journal files older than the specified time
journalctl --vacuum-size=size	Remove old journal files until the total size is below the specified size
journalctl -o json-pretty	Output logs in pretty JSON format

Command/Configuration	Description
/etc/rsyslog.conf	Main configuration file for rsyslog
/etc/rsyslog.d/	Directory for additional configuration files
sudo systemctl restart rsyslog	Restart the rsyslog service
logger "message"	Add a message to the system log
/var/log/messages	General system log
/var/log/secure	Authentication and security related messages
/var/log/maillog	Mail server logs
/var/log/cron	Cron job logs
/var/log/boot.log	System boot log
/var/log/dmesg	Kernel ring buffer log

Command	Description
top	Display real-time system information including tasks and load
htop	Interactive process viewer (requires installation)
top -u username	Show only processes for a specific user
top -p PID	Show only the specified PID(s)
htop -u username	Show only processes for a specific user (in htop)

Command	Description
free	Display memory usage
free -h	Display memory usage in human-readable format
free -m	Display memory usage in megabytes
free -g	Display memory usage in gigabytes

Command	Description
vmstat	Display virtual memory statistics
vmstat 1	Display virtual memory statistics every second
vmstat -s	Display memory statistics
vmstat -d	Display disk statistics
vmstat -t	Display timestamps with the output

Command	Description
iostat	Display CPU and I/O statistics
iostat -x	Display extended statistics
iostat -d	Display device utilization statistics
iostat -c	Display only CPU statistics
iostat -p ALL	Display statistics for all devices and partitions

Command	Description
mpstat	Display CPU usage
mpstat -P ALL	Display CPU usage for all processors
mpstat 1 5	Display CPU usage every second for 5 times

Command	Description
sar	Collect and report system activity
sar -u 1 3	Report CPU utilization every second for 3 times
sar -r	Report memory utilization
sar -n DEV	Report network statistics
sar -b	Report I/O and transfer rate statistics

Command	Description
netstat -tuln	List all listening ports
netstat -i	Display network interfaces
netstat -rn	Display routing table
netstat -s	Display network statistics
ss -tuln	List all listening ports (ss command)
ss -i	Display network interfaces (ss command)
ss -rn	Display routing table (ss command)
ss -s	Display network statistics (ss command)

Command	Description
iftop	Display real-time network bandwidth usage
iftop -i interface	Display network bandwidth usage for a specific interface
iftop -P	Show ports
iftop -n	Show numerical addresses rather than resolving hosts

Command	Description
tcpdump -i interface	Capture packets on a specific interface
tcpdump -n host host	Capture packets to/from a specific host
tcpdump -nn port port	Capture packets on a specific port
tcpdump -w file.pcap	Write captured packets to a file
tcpdump -r file.pcap	Read packets from a file

Directory/File	Description
/proc/cpuinfo	Detailed information about the CPU, such as model, cores, and speed
/proc/meminfo	Detailed information about memory usage
/proc/version	Kernel version and build information
/proc/cmdline	Kernel command line used to boot the system
/proc/devices	Lists all character and block devices currently configured
/proc/diskstats	Disk I/O statistics
/proc/uptime	System uptime information
/proc/loadavg	Load average of the system
/proc/mounts	Mounted filesystems
/proc/partitions	Information about disk partitions
/proc/swaps	Swap space utilization
/proc/sys	Kernel tunable parameters (sysctl)
/proc/sys/kernel	Kernel-related parameters
/proc/sys/net	Network-related parameters
/proc/net	Network status information
/proc/interrupts	Number of interrupts per CPU per I/O device
/proc/iomem	Memory map for the system
/proc/ioports	I/O port usage
/proc/modules	Loaded kernel modules
/proc/kallsyms	Kernel symbol table
/proc/kcore	Pseudo-file representing the physical memory of the system
/proc/slabinfo	Kernel slab allocator information
/proc/self	Process-specific information for the current process
/proc/self/cmdline	Command line of the current process
/proc/self/environ	Environment variables of the current process
/proc/self/exe	Symlink to the executable of the current process
/proc/self/status	Current process status information
/proc/self/limits	Resource limits of the current process
/proc/self/mounts	Mounts of the current process
/proc/self/cgroup	Cgroup membership of the current process
/proc/self/fd	File descriptors opened by the current process
/proc/self/fdinfo	Detailed information about file descriptors
/proc/self/maps	Memory maps of the current process
/proc/self/smaps	Extended memory maps of the current process
/proc/self/mem	Memory of the current process
/proc/self/task	Tasks (threads) of the current process
/proc/[pid]/	Information specific to process with PID
/proc/[pid]/cmdline	Command line of the process with PID
/proc/[pid]/environ	Environment variables of the process with PID
/proc/[pid]/exe	Symlink to the executable of the process with PID
/proc/[pid]/status	Status information of the process with PID
/proc/[pid]/limits	Resource limits of the process with PID
/proc/[pid]/mounts	Mounts of the process with PID
/proc/[pid]/cgroup	Cgroup membership of the process with PID
/proc/[pid]/fd	File descriptors opened by the process with PID
/proc/[pid]/fdinfo	Detailed information about file descriptors of the process with PID
/proc/[pid]/maps	Memory maps of the process with PID
/proc/[pid]/smaps	Extended memory maps of the process with PID
/proc/[pid]/mem	Memory of the process with PID
/proc/[pid]/task	Tasks (threads) of the process with PID

Hotkey	Description
Space	Toggle play/pause
f	Toggle fullscreen
m	Mute/unmute audio
9 / (	Decrease volume
0 / )	Increase volume
[	Decrease playback speed
]	Increase playback speed
{	Halve playback speed
}	Double playback speed
backspace	Reset playback speed to normal
Left Arrow	Seek backward 5 seconds
Right Arrow	Seek forward 5 seconds
Up Arrow	Seek forward 60 seconds
Down Arrow	Seek backward 60 seconds
Shift+Left Arrow	Seek backward 1 second
Shift+Right Arrow	Seek forward 1 second
Ctrl+Left Arrow	Seek backward 10 minutes
Ctrl+Right Arrow	Seek forward 10 minutes
.	Move forward one frame (pause required)
,	Move backward one frame (pause required)
o	Show file info
I	Show codec info
q	Quit
Q	Force quit (without saving the resume position)
s	Take a screenshot
S	Take a screenshot without subtitles
Ctrl+s	Take a screenshot and include the OSD
T	Toggle displaying time
Ctrl+o	Cycle through OSD (On-Screen Display) levels
v	Toggle subtitles
j	Cycle through subtitles
J	Cycle through secondary subtitles
#	Toggle subtitle visibility
z	Adjust subtitle delay backward
x	Adjust subtitle delay forward
r	Rotate video
p	Toggle between current and previous subtitle track
l	Adjust audio delay backward
k	Adjust audio delay forward
Ctrl++	Increase subtitle font size
Ctrl+-	Decrease subtitle font size
Alt++	Increase subtitle border size
Alt+-	Decrease subtitle border size
Ctrl+r	Toggle random playback
Ctrl+shift+r	Toggle looping playback
Ctrl+p	Toggle playlist navigation display
Ctrl+u	Reload playlist
Ctrl+Enter	Toggle between fullscreen and windowed mode
Esc	Exit fullscreen or close OSD menu
h	Seek to the previous chapter
l	Seek to the next chapter
y	Adjust subtitle delay back by 0.1 seconds
Y	Adjust subtitle delay forward by 0.1 seconds
t	Toggle stay-on-top mode
Ctrl+f	Toggle autofit
Ctrl+c	Copy current file path to clipboard
Ctrl+v	Paste URL/file path from clipboard and open