Tag: Linux Cheat Sheet

# Display Linux system information

uname -a

# Display kernel release information

uname -r

# Display the linux kernel name

uname -s

# Get the linux kernel version

uname -v

# Get network node hostname

uname -n

# Get machine hardware architecture (i386, x86_64, etc.)

uname --m

# Get processor type

uname -p

# Get hardware platform

uname -i

# Get operating system information

uname -o

# Show which version of redhat installed

cat /etc/redhat-release

# Show how long the system has been running + load

uptime

# Show system host name

hostname

# Display the IP addresses of the host

hostname -I

# Show system reboot history

last reboot

# Show the current date and time

date

# Show this month’s calendar

cal

# Display who is online

w

# Who you are logged in as

whoami

# Get Hardware information

sudo lshw

# View the summary of your detailed hardware profile

lshw -short

# Print your hardware profile to an HTML file as a superuser

sudo lshw -html > [filename.html]

# Get CPU information

lscpu

# Get block device information

lsblk

# View much more detailed information about all the devices

lsblk -a

# ALT Key

ALT+A	Go to the beginning of a line.
ALT+B	Move one character before the cursor.
ALT+C	Suspends the running command/process.
ALT+D	Closes the empty Terminal (I.e it closes the Terminal when there is nothing typed). It also deletes all characters after the cursor.
ALT+F	Move forward one character.
ALT+T	Swaps the last two words.
ALT+U	Capitalize all characters in a word after the cursor.
ALT+L	Uncapitalize all characters in a word after the cursor.
ALT+R	Undo any changes to a command that you have brought from the history if you’ve edited it.

# CTRL Key

CTRL+A	Quickly move to the beginning of the line.
CTRL+B	To move backward one character.
CTRL+C	Stop the currently running command.
CTRL+D	Delete one character backward.
CTRL+E	Move to the end of the line.
CTRL+F	Move forward one character.
CTRL+G	Leave the history searching mode without running the command.
CTRL+H	Delete the characters before the cursor, the same as Backspace.
CTRL+J	Same as Enter/ Return key.
CTRL+K	Delete all characters after the cursor.
CTRL+L	Clears the screen and redisplay the line.
CTRL+M	Same as CTRL+J or RETURN.
CTRL+N	Display the next line in the command history.
CTRL+O	Run the command that you found using reverse search i.e CTRL+R.
CTRL+P	Displays the previous line in the command history.
CTRL+R	Searches the history backward (Reverse search).
CTRL+S	Searches the history forward.
CTRL+T	Swaps the last two characters.
CTRL+U	Delete all characters before the cursor (Kills backward from point to the beginning of the line).
CTRL+V	Makes the next character typed verbatim.
CTRL+W	Delete the words before the cursor.
CTRL+X	Lists the possible filename completions of the current word.
CTRL+XX	Move between the start of the command line and the current cursor position (and back again).
CTRL+Y	Retrieves the last item that you deleted or cut.
CTRL+Z	Stops the current command.
CTRL+[	Equivalent to ESC key.

# Miscellaneous

!!	Repeat last command
!name	Run the last command starting with ‘name’
!name:p	Print the last command starting with ‘name’
!$	Last argument of the previous command
ALT-.	Last argument of the previous command
!*	All arguments of the previous command
^name^another	Run the previous command, replacing ‘name’ with ‘another’

# Show enviro­nment variables

env

# Output value of $NAME variable

echo $NAME

# Set $NAME to value

export NAME=value

# Executable search path

$PATH

# Home directory

$HOME

# Current shell

$SHELL

# List all files including hidden file

ls -a

# Recursive list

ls -R

# Reverse order

ls -r

# Colored list [=always/never/auto]

ls --color

# List directories – with ‘ */’

ls -d

# Add one char of */=>@| to enteries

ls -F

# List file’s inode index number

ls -i

# Sort by last modified

ls -t

# Sort by file size

ls -S

# List file size

ls -s

# List with long format – show permissions

ls -l

# List long format including hidden files

ls -la

# List long format with readable file size

ls -lh

# List with long format with file size

ls -ls

# One file per line

ls -1

# Comma-­sep­arated output

ls -m

# Quoted output

ls -Q

# Sort by extension name

ls -X

# Display messages in kernel ring buffer

dmesg

# Reports information about the cpu and processing units

lscpu

# Extracts the information from different /proc files

lshw -short

# Report detailed and brief information about multiple different hardware components

hwinfo --short

# Lists out all the PCI buses and details about the devices connected to them

lspci 

# Display USB devices

lsusb 

# Lists out the scsi/sata devices like hard drives and optical drives

lsscsi

# Display CPU information

cat /proc/cpuinfo

# Display memory information

cat /proc/meminfo

# Display DMI/SMBIOS (hardware info) from the BIOS

dmidecode

# Show info about disk sda

hdparm -i /dev/sda

# Perform a read speed test on disk sda

hdparm -tT /dev/sda

# Test for unreadable blocks on disk sda

badblocks -s /dev/sda

# List out information all block devices

lsblk

# Reports various partitions, their mount points and the used and available space on each

df -H

# Mount/unmount and view mounted file systems

mount | column -t

# Filter out only those file systems that you want to see

mount | column -t | grep ext

# Check the amount of used, free and total amount of RAM on system with the free command.

free -m

# Gets information about sata devices like hard disks

sudo hdparm -i /dev/sda

# CPU information

 cat /proc/cpuinfo

# Memory information

cat /proc/meminfo

# Linux/kernel information

cat /proc/version

# Display and manage the top processes

top

# Display virtual memory statistics

vmstat 1

# Display processor related statistics

mpstat 1

# Display I/O statistics

iostat 1

# List all open files

lsof

# List files opened by user

lsof -u user

# Capture and display all packets on interface eth0

tcpdump -i eth0

# Monitor all traffic on port 80 ( HTTP )

tcpdump -i eth0 'port 80'

# Monitoring incoming and outgoing network packets statistics as well as interface statistics

netstat -a | more

# Finding the exact process and high used disk read/writes of the processes

iotop

# Display free and used memory ( -h for human-readable, -m for MB, -g for GB)

free -h

# Execute “df -h”, showing periodic updates

watch df -h

# Display the user and group ids of your current user

id

# Display the last users who have logged onto the system

last

# To show all the users who were present at a specified time

last -ap now

# Find the details of a recent login of all users or of a given user as follows

lastlog

# Show who is logged into the system

who

# Show who is logged in and what they are doing

w

# Create a group named “groupname”

groupadd groupname

# Create an account named kim, with a comment of “Kim Kardashian” and create the user’s home directory

useradd -c "Kim Kardashian" -m kim

# Add the kim account to the sales group

usermod -aG sales kim

# Delete the kim account

userdel john

# Display all network interfaces and ip address

ifconfig -a

# Display eth0 address and details

ifconfig eth0

# Query or control network driver and hardware settings

ethtool eth0

# Print kernel module info

ethtool -i eth0

# Print eth0 traffic statistics

ethtool -S eth0

# Print RX, TX and auto-negotiation settings

ethtool -a eth0 

# Blink LED

ethtool -p eth0 

# Display whois information for domain

whois domain

# Send ICMP echo request to host

ping host

# Network Connec­tions

watch ss -tp

# Display listening tcp and udp ports and corresponding programs

netstat -nutlp

# TCP connec­tions

netstat -ant

# UDP Connec­tions

netstat -anu

# Connec­tions with PIDs

netstat -tulpn

# Display DNS information for domain

dig domain

# Display DNS ip address for domain

host domain

# Display the network address of the host name

hostname -i

# Display all local ip addresses

hostname -I

# Download file http://domain.com/filename

wget http://domain.com/filename

# Create tar named archive.tar containing directory

tar cf archive.tar directory

# Extract the contents from archive.tar

tar xf archive.tar

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

tar czf archive.tar.gz directory

# Extract a gzip compressed tar file

tar xzf archive.tar.gz

# Create a tar file with bzip2 compression

tar cjf archive.tar.bz2 directory

# Extract a bzip2 compressed tar file

tar xjf archive.tar.bz2

# List content of tar file

tar -tvf archive.tar

# Search for a package by keyword

yum search keyword

# Install a Package with YUM

yum -y install packetname

# Remove/Uninstall a Package with YUM

yum -y remove packetname

# Display description and summary information about package

yum info package

# Updating a Package

yum update packetname

# List a Package

yum list packetname

# Install package from local file named package.rpm

rpm -i package.rpm

# List all available packages

yum list | less

# List all installed packages

yum list installed | less

# Connect to host as your local username

ssh host

# Connect to host as user

ssh user@host

# Connect to host using port

ssh -p port user@host

# Generating public-private keys

ssh-keygen

# Create a key pair

ssh-keygen -t rsa

# Copy Public SSH Key

ssh-copy-id hostname_or_IP

# Edit SSH Config File

sudo vim /etc/ssh/sshd_config

# Restart SSH service

sudo ssh service restart

# Show free and used space on mounted filesystems

df -h

# Show free and used inodes on mounted filesystems

df -i

# Shows the file system’s complete disk usage even if the Available field is 0

df -a

# Display disks partitions sizes and types

fdisk -l

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

du -ah

# Display total disk usage off the current directory

du -sh

# Shows the disk usage along with each block’s filesystem type (e.g., xfs, ext2, etc.)

df -T

# Go up a directory

cd ..

# Go to the $HOME directory

cd

# Change to the /etc directory

cd /etc

# Show current directory

pwd

# Make directory dir

mkdir dir

# List files

ls

# Find files and directories by name

locate name

# Search for pattern in file

grep pattern file

# Search recursively for pattern in directory

grep -r pattern directory

# Find files in /home/ that start with “filename”.

find /home/owner -name filename*

# Find files owner by “filename” in /home/

find /home/ -user filename

# Find files modifed less than “number” minutes ago in home

find /home/ -mmin number

# Search files larger than 100MB in /home

find /home -size +100M

# Search for pattern in files

grep pattern files

# Case insens­itive search

grep -i

# Recursive search

grep -r

# Inverted search

grep -v

# Show matched part of file only

grep -o

# Find binary / source / manual for command

whereis command

# Show your currently running processes

ps

# Show all the currently running processes on the system.

ps -ef

# Show process information for processname

ps -ef | grep processname

# Show real time processes

top

# Interactive process viewer (top alternative)

htop

# Kill process with id pid

kill pid

# Kill all processes named processname

killall processname

# Kill process with name processname

pkill processname

# Start program in the background

program &

# Display stopped or background jobs

bg

# Brings the most recent background job to foreground

fg

# Brings job n to the foreground

fg n

# List all files in a long listing (detailed) format

ls -al

# Display the present working directory

pwd

# Create a directory

mkdir directory

# Create file1

touch file1

# Concat­enate files and output

cat file1 file2

# View and paginate file1

less file1

# Get type of file1

file file1

# Remove/ delete file

rm file

# Remove the directory and its contents recursively

rm -r directory

# Force removal of file without prompting for confirmation

rm -f file

# Forcefully remove directory recursively

rm -rf directory

# Copy file1 to file2

cp file1 file2

# Rename or move file1 to file2

mv file1 file2

# Create symbolic link to linkname

ln -s /path/to/file linkname

# Create an empty file or update the access and modification times of file1.

touch file1

# Show first 10 lines of file1

head file1

# Show last 10 lines of file1

tail file1

# Output last lines of file1 as it changes

tail -F file1

# Change mode of file to 775

chmod 775 file

# Recurs­ively chmod folder to 600

chmod -R 600 folder

# Change file owner to user and group to group

chown user:group file

# Copy *.html files from server to the local /tmp folder.

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

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

scp file.txt server:/tmp

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

scp -r server:/var/www /tmp

# Synchronize /home to /backups/home

rsync -a /home /backups/