How to add public key to authorized_keys?

To add your public key to the authorized_keys file on the target system, follow these steps:

Create the .ssh directory (if it doesn't already exist):
```
mkdir -p ~/.ssh
```
Append your public key to the authorized_keys file:
```
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
```
This command assumes your public key is located at ~/.ssh/id_rsa.pub. Adjust the path if your key is stored elsewhere.
Verify the contents of the authorized_keys file:
```
cat ~/.ssh/authorized_keys
```
You should see your public key listed.
Set the correct permissions for the authorized_keys file:
```
chmod 600 ~/.ssh/authorized_keys
```
This command ensures that only the owner can read and write to the file, which is a security requirement.

After completing these steps, you should be able to SSH into the target system without needing to enter a password.