ALL IN ONE

passwd

Change the current user's password.

sudo -i

Switch to the root account with root's

environment. (Login shell.)

sudo -s

Execute your current shell as root.

(Non-login shell.)

sudo -l

List sudo privileges for the current user

visudo

Edit the sudoers configuration file

getenforce

Display the current SELinux mode

sestatus

Display SELinux details such as the current

SELinux mode

setenforce 0

Change the current SELinux mode to

Permissive. (Does not survive a reboot.)

setenforce 1

Change the current SELinux mode to

Enforcing. (Does not survive a reboot.)

SELINUX=enforcing

Set the SELinux mode to enforcing on boot

by using this setting in the /etc/selinux/config file.

SELINUX=permissive

Set the SELinux mode to permissive on boot

by using this setting in the /etc/selinux/config file.

SELINUX=disabled

Set the SELinux mode to disabled on boot by

using this setting in the /etc/selinux/config file

cd ..

To go up one level of the directory tree. (Change into

the parent directory.)

cd

Go to the $HOME directory

cd /etc

Change to the /etc directory

alias goto='cd /etc/'

Create goto alias for command cd /etc/

yum search keyword

Search for a package by keyword

yum install package

Install package

yum info package

Display description and summary information about package for RHEL based systems

rpm -i package.rpm

Install package from local file named package.rpm

yum remove package

Remove/uninstall package for RHEL based systems

yum update package

Update package with name package for RHEL based systems

tar zxvf sourcecode.tar.gz cd sourcecode ./configure make make install

Install software from source code.

apt-get update

Update package list for Debian based systems.

apt-get upgrade

Upgrade all installed packages to their newest version for Debian based systems

apt-get install package

Install package with name package for Debian based systems

apt-remove package

Remove package with name package for Debian based systems

grep pattern file

# Search for pattern in file

grep -r pattern directory

# Search recursively for pattern in directory

locate name

# Find files and directories by name

find /home/john -name 'prefix*'

# Find files in /home/john that start with "prefix"

find /home -size +100M

# Find files larger than 100MB in /home

whereis program

# Display the location of the binary, source and

manual page files of program

which program

# Display the path of executable that would run if

program is executed

df -h

Show free and used space on mounted filesystems

df -i

Show free and used inodes on mounted filesystems

fdisk -l

Display disks partitions sizes and types

du -ah

Display disk usage for all files and directories in human readable format

du -sh

Display total disk usage off the current directory

du -a directory

Display size of all files in directory

findmnt

List all mounted file systems with details

ssh host

Connect to host as your local username

ssh user@host

Connect to host as user

ssh -p port user@host

Connect to host using port

ssh-keygen

Create a new SSH key pair.

ssh-copy-id user@host

Copy SSH key to the remote host to enable passwordless logins for user

scp file.txt server:/tmp

Secure copy file.txt to the /tmp folder on server

scp server:/var/www/*.html /tmp

Copy *.html files from server to the local

/tmp folder

scp -r server:/var/www /tmp

Copy all files and directories recursively from server to the current system's /tmp folder

rsync -a /home /backups/

Synchronize /home to /backups/home

rsync -avz /home server:/backups/

Synchronize files/directories between the local and remote system with compression enabled

ftp host

Connect to FTP server on the remote host.

chown john /path/to/file

Change ownership of /path/to/file to

john

chgrp sales /path/to/file

Change group ownership of

/path/to/file to group sales

dmesg

Display messages in kernel ring buffer

journalctl

Display logs stored in the systemd

journal

journalctl -u servicename

Display logs for a specific unit (service)

ip a

Display all network interfaces and IP address

ip addr show dev eth0

Display eth0 address and details

ethtool eth0

Query or control network driver and hardware settings

ping host

Send ICMP echo request to host

whois domain

Display whois information for domain

dig domain

Display DNS information for domain

dig -x IP_ADDRESS

Reverse lookup of IP_ADDRESS

host domain

Display DNS IP address for domain

hostname -i

Display the network address of the host name.

hostname -I

Display all local IP addresses of the host.

wget http://domain.com/file

Download http://domain.com/file

netstat -nutlp

Display listening tcp and udp ports and corresponding programs

ifconfig

Display information about network interfaces

traceroute host

Display the path that packets take to host

tcpdump

Capture and analyze network traffic

tar cf archive.tar directory

Create tar named archive.tar containing

directory

tar xf archive.tar

Extract the contents from archive.tar

tar czf archive.tar.gz directory

Create a gzip compressed tar file name archive.tar.gz

tar xzf archive.tar.gz

Extract a gzip compressed tar file

tar cjf archive.tar.bz2 directory

Create a tar file with bzip2 compression

tar xjf archive.tar.bz2

Extract a bzip2 compressed tar file

ls -al

List all files in a long listing (detailed) format

pwd

Display the present working directory

mkdir directory

Create a directory

rm file

Remove (delete) file

rm -r directory

Remove the directory and its contents recursively

rm -f file

Force removal of file without prompting for confirmation

rm -rf directory

Forcefully remove directory recursively

cp file1 file2

Copy file1 to file2

cp -r source_directory destination

Copy source_directory recursively to destination. If destination exists

mv file1 file2

Rename or move file1 to file2. If file2 is an existing directory

ln -s /path/to/file linkname

Create symbolic link to linkname

touch file

Create an empty file or update the access and modification times of file

cat file

View the contents of file

less file

Browse through a text file

head file

Display the first 10 lines of file

tail file

Display the last 10 lines of file

tail -f file

Display the last 10 lines of file and "follow" the file as it grows.

ps

Display currently running processes

ps -ef

Display all currently running processes on the system

ps -ef | grep processname

Display process information for processname

top

Display and manage the top processes

htop

Interactive process viewer (top alternative)