Alhaditech

Linux/ubunut Cheat sheet

To create a new user in a Linux-based operating system, you can use the adduser or useradd command. Here are the basic commands to create a new user:

Using adduser (more user-friendly):

sudo adduser username

Using useradd:

sudo useradd username

Change password command 

sudo passwd username

Access server with port change other than 22 and with key pair commands

ssh username@server_ip -p 2222
while with ssh key 

ssh -i ~/.ssh/id_rsa username@server_ip -p 2222

SSH key pair generation 

ssh-keygen -t rsa -b 4096

chmod command

 

chmod is a common command that modifies a file or directory’s read, write, and execute permissions. In Linux, each file is associated with three user classes – owner, group member, and others.

chmod 777 note.txt

 chown command

The chown command lets you change the ownership of a file, directory, or symbolic link to a specified username.

Here’s the basic format:

chown linuxuser2 filename.txt

sudo chown -R odoo:odoo folder_name

add user into sudo group

sudo usermod -aG sudo newusername

pwd

Use the pwd command to find the path of your current working directory.

mkdir

cd

To navigate through the Linux files and directories

ls command 

The ls command lists files and directories within a system

rm

locate command

locate -i school*note

The command will search for files that contain the words school and note

find command

Use the  find  command to search for files within a specific directory and perform subsequent operations. Here’s the general syntax
find /home -name notes.txt

df

Use the df command to report the system’s disk space usage

df -h

These are some acceptable options to use:

• df -m displays information on the file system usage in MBs.
• df -k displays file system usage in KBs.
• df -T shows the file system type in a new column.

du command

If you want to check how much space a file or a directory takes up, 

du /home/user/Documents

Adding a flag to the du command will modify the operation, such as:

• -s offers the total size of a specified folder.
• -m provides folder and file information in MB
• k displays information in KB.
• -h informs the last modification date of the displayed folders and files.

 kill command

 
Use the  kill command to terminate an unresponsive program manually. It will signal misbehaving applications and instruct them to close their processes.

ps ux

After knowing what signal to use and the program’s PID, enter the following syntax:

kill [signal_option] pid 

 

ping command

The ping command is one of the most used commands in Linux for checking whether a network or a server is reachable

 
history command
With  history, the system will list up to 500 previously executed commands, allowing you to reuse them without re-entering. Keep in mind that only users with  sudo privileges can execute this command.

history [option]

This command supports many options, such as:

• -c clears the complete history list.
• -d offset deletes the history entry at the OFFSET position.
• -a appends history lines.

indetify laptop model 

sudo dmidecode -s system-product-name


Bios information command

sudo dmidecode -t bios