How to export private key? (GnuPG)

Question

I have successfully created GnuPG public/private key pair using RSA and RSA algorithm. How can I export a public key and private key in the form of file with the .asc extension?

Answer 1

Hint 1: gpg calls private keys 'secret' because PGP dates from before people settled on the names 'private' key for the half of an asymmetric pair held by (ideally) only one party versus 'secret' key for a symmetric value usually held by two or more mutually trusting parties but nobody else.

man gpg2 | less "+/export-secret" then n (go to second match) shows:

   --export-secret-keys

   --export-secret-subkeys
          Same  as --export, but exports the secret keys instead.  This is
          normally not very useful and a security risk.  The  second  form
          of  the  command  has  the special property to render the secret
          part of the primary key useless; this  is  a  GNU  extension  to
          OpenPGP  and  other  implementations can not be expected to suc-
          cessfully import such a key.  See the option  --simple-sk-check-
          sum  if  you  want  to import such an exported key with an older
          OpenPGP implementation.

Hint 2: you can output to a file by just redirecting, or using (either of)

   --output file

   -o file
          Write output to file.

However, people usually use the .asc extension for files in 'ASCII armor(ed)' format, which is base64 with dashes-BEGIN and dashes-END lines and sometimes (including here) 822/MIME-style headers. If you want not just a file named .asc, but a file in the usual .asc format, use (either of)

   --armor

   -a     Create ASCII armored output.   The  default  is  to  create  the
          binary OpenPGP format.

TLDR:

gpg2 --export-secret-keys -a -o file.asc [keyid ...]