Regular Linux yum update

1. Check your latest patches status:

sudo su 

yum check-update

2. Update all definitions to latest versions:

yum update 

Amazon AWS Linux - Enable password authentification only for certain user

1. Add new user part of sudoers:
sudo su
useradd dtech

2. Create password:
passwd dtech
 
3. Make sure it has sudo rights:
cd /etc/sudoers.d/
touch dtech_other_sudoers
chmod 440 dtech_other_sudoers
vi dtech_other_sudoers

dtech  ALL=(ALL)       NOPASSWD: ALL

# This comment is here to have new line at end of file
4. Enable password authentification:
vi /etc/ssh/sshd_config

5. Add following lines to the very end of the file:
Match User dtech
    PasswordAuthentication yes
  
6. Restart sshd service
service sshd restart

7. Test and you shall now get password prompt only for your user:
ssh dtech@35.171.158.153
dtech@35.171.158.153's password:
Last login: Wed Dec 25 22:17:05 2019

Delete a file that begins with "-"/ hyphen, dash or minus on Linux

Use the following command:

rm --  -filename

Remove CSS round border from iOS devices

Following CSS options must be enabled for your element:

element{
border-radius:0;
-webkit-appearance: none;
}

Linux: Find and replace text from file

sed -i 's/text-to-replace/text-new/g' destination-file-path

Linux: Find and remove file in one command

Navigate to folder, find the file and remove using the following command. It also asks for confirmation before removing:

cd /destination-folder-path && find -type f -name filename -exec rm -i {} \;

PHP - Get last element from array

//array is called here $arrayVariable

$lastElement=end($arrayVariable);

Example: 
If $arrayVariable=["apple","pear","peach","cherry"], the function above is to return cherry.