How to find or generate a SSH key on Linux system

To find or generate a SSH key on Linux system

Check for existing SSH keys on your computer. Skip to Step 4 if you already have one and want to use that one.
First, we will check for existing ssh keys:
$ cd ~/.ssh

Backup and remove existing SSH keys to create one.
If there is already a SSH directory you’ll want to back the old one up and remove it. $ ls Lists all the subdirectories in the current ssh directory
$ ls config id_rsa id_rsa.pub known_hosts
Make a subdirectory called “key_backup” in the current directory
$ mkdir key_backup
Copy the id_rsa and id_rsa.pub files into key_backup
$ cp id_rsa* key_backup
Remove existing SSH directory and key.
$ rm id_rsa*
Generate a new SSH key. To generate a new SSH key, enter the code below. We will create new key in the current directory so when asked to enter a file in which to save the key, just press enter.
$ ssh-keygen -t rsa -C "your_email@youremail.com" Generating public/private rsa key pair. Enter file in which to save the key (/root/.ssh/id_rsa):<press enter>
Now you need to enter a passphrase.
Enter passphrase (empty for no passphrase):<enter a passphrase> Enter same passphrase again:<enter passphrase again>
Which should give you something like this:
Your identification has been saved in /root/.ssh/id_rsa. Your public key has been saved in /root/.ssh/id_rsa. The key fingerprint is: 01:0f:f4:3b:ca:85:d6:12:a1:7d:f2:64:9d:f0:a2:db user_name@username.com The key's randomart image is:
```
  +--[ RSA 2048]----+
  |         .+* +o. |
  |          . +EXo |
  |             O.=o|
  |            +o=o.|
  |        S   oo  .|
  |         . .     |
  |          .      |
  |                 |
  |                 |
  +-----------------+
```
Go to the location where your SSH key is saved and open it
$ gedit /root/.ssh/id_rsa.pub
Everything in this file is your SSH key. It looks something like,
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDNG2SI+C7y4KvCwR2YC2vFmmHCrHkMulfzfZRxbY+Yp2SxbUG4umBuk7aRp+5A1/8fvEA9WTY0z+E+7M10y6108HnjXqF7j+9cRlVqdaaroW9T6xz3C5efHLTuhSfGtYJ1BGprrnhsBWSPC2JKB6zK9RZ7pIXXAUbIyHaokcgcs7xofAqLoeLdE2ER9HmrZTj17wELHsJzztB4jJBGr4wWXTcb82gbb0B12nkbATpTzYVtlpLT1PnlJLsoNuvw3ZGwx8GmMWulOFFL7IfrT0tbajKZfvlXT22Y1Wixuq3YFjltS5OQjgPC4LQTeWb+qvB2Lj6mrvJsVCeOkKmGrZ/J your_email@youremail.com