ssh \<username>@\<serverIP>

List all the files in the directory

ls -l gives list files with permissions
ls -al gives hidden files as well

Be able to print the current directory

Changing directory

cd \<path> navigate to the respective directory
cd .. jump back directory
cd naviagate to home

touch \<filename> create a new file
touch \<filename1> <filename2> create several files
touch \<filename>{1..10} create 10 files

echo \<message> print the message
echo \<message> \> \<filename> Add message to the file

nano \<filename> edit a file
To save use ctrl + X and Y and Enter to save

vim \<filename> edit a file
Hit I to start editing When done use hit ESC and :wq

cat \<filename> Read content of a file

shred \<filename> Don't let anyone to read the file.

mkdir \<directory name> create a new directory

cp \<file name> \<path where to copy> Copy file to a given path mv \<file name> \<path where to move> Move file to the given path

rm \<file name> Remove a file

rmdir \<directory name> For an empty directory removal rm -r \<directory name> To remove a directory with files in it

ln -s \<file name> <link> Can create a link to a file with -s switch for soft

Clear the terminal

Tells who you are😄 (returns the username)

useradd \<name> Create a new user

sudo \<command which needs permission> Uses when asked for permission Need to enter the password for user

Can reverse the command useradd

su <username> Can switch user

Exit temparary user. (can use in several occasions)

passwd <username> Can change the password of the user

sudo apt update Needs to update before install sudo apt install <package> Install packages

Needs to install finger package first

finger \<username> Can be used to inspect another user

man \<command> Can get help with things that don't know

whatis \<command> Faster than man command to get help

whereis \<command> To findout where the command is

wget \<link> Help to get stuff from the internet (download)

curl \<link> Help to get stuff from the internet

zip \<zip file> <file name> Make a zip file

unzip <zip file name> Unzip the file

less <file name> Can read one page at a time. (substitution for cat command)

head <file name> Output only the begining of the file

tail <file name> Output only the ending of the file

cmp <file1> <file2> Compare two files and check whether any differences exist.

diff <file1> <file2> List the differences of the two files

cat <file name> | sort The file is sorted in alphabatical order

sudo find <the directory> -name "<search key>" Find the search key sudo find <the directory> -type f -name "." Find all hidden files find <the directory> -type f -empty Finds all empty directories find <the directory> -perm /a=x Finds all executable files

Change the permissions of the file

chmod <permission> <file name> To change permission of the file.

chown <user> <file name> Changing owner of the file

Gives IP address of the machine

Returns the ip address

Return information about the DNS server (including IP address)

ping <name of the website/ipaddress>

traceroute <name of the website>To see the path through the internet to get to a website

To check what ports in use.

sudo iptables -I INPUT -p tcp -, tcp --dport <port> -j ACCEPTTo allow a specific port through the firewall

uname -a To find information about the system.

A quick little calendar :)

To check how much memeory available in system and swap space.

To check how much space available (To be more specific use df -H)

To list all processes

ps -aux More details

List processes running in real time

kill -KILL <pid> or kill -9 <pid> To kill the process with given id.

systemctl stop <service name> Stop a specific service.
systemctl start <service name> Start a specific service.
systemctl restart <service name> Restart a specific service

Return a list of commands used.

sudo reboot To reboot the system

sudo shutdown To shutdown the system after 1 minute
sudo shutdown -h now To shutdown the system now