how to generate a new key with gpg encryption

Assuming that you have installed the gpg package on your machine.

[oracle@Linux03 ~]$ gpg --gen-key
gpg (GnuPG) 2.0.14; Copyright (C) 2009 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Please select what kind of key you want:
   (1) RSA and RSA (default)
   (2) DSA and Elgamal
   (3) DSA (sign only)
   (4) RSA (sign only)
Your selection? 1
RSA keys may be between 1024 and 4096 bits long.
What keysize do you want? (2048)
Requested keysize is 2048 bits
Please specify how long the key should be valid.
         0 = key does not expire
      <n>  = key expires in n days
      <n>w = key expires in n weeks
      <n>m = key expires in n months
      <n>y = key expires in n years
Key is valid for? (0) 0
Key does not expire at all
Is this correct? (y/N) y

GnuPG needs to construct a user ID to identify your key.

Real name: arvind
Email address: arvind@gmail.com
Comment: arvind gpg test
You selected this USER-ID:
    "arvind (arvind gpg test) <arvind@gmail.com>"

Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? o
You need a Passphrase to protect your secret key.

can't connect to `/home/oracle/.gnupg/S.gpg-agent': No such file or directory

(pinentry-gtk-2:3073): GLib-GObject-CRITICAL **: Object class GtkSecureEntry doesn't implement property 'editing-canceled' from interface 'GtkCellEditable'

(pinentry-gtk-2:3076): GLib-GObject-CRITICAL **: Object class GtkSecureEntry doesn't implement property 'editing-canceled' from interface 'GtkCellEditable'
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
gpg: key 17DC5B7A marked as ultimately trusted
public and secret key created and signed.

gpg: checking the trustdb
gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model
gpg: depth: 0  valid:   1  signed:   0  trust: 0-, 0q, 0n, 0m, 0f, 1u
pub   2048R/17DC5B7A 2016-09-02
      Key fingerprint = 7B68 5877 A612 F10A AD43  5E01 2320 7F55 17DC 5B7A
uid                  arvind (arvind gpg test) <arvind@gmail.com>
sub   2048R/5C9DA3C6 2016-09-02



[oracle@Linux03 ~]$ gpg --list-keys
/home/oracle/.gnupg/pubring.gpg
-------------------------------
pub   2048R/17DC5B7A 2016-09-02
uid                  arvind (arvind gpg test) <arvind@gmail.com>
sub   2048R/5C9DA3C6 2016-09-02

[oracle@Linux03 ~]$