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### 4.3 Configuration files

There are a few configuration files to control certain aspects of `gpg2`’s operation. Unless noted, they are expected in the current home directory (see option --homedir).

`gpg.conf`

  This is the standard configuration file read by `gpg2` on startup. It may contain any valid long option; the leading two dashes may not be entered and the option may not be abbreviated. This default name may be changed on the command line (see gpg-option --options). You should backup this file.

Note that on larger installations, it is useful to put predefined files into the directory `/etc/skel/.gnupg` so that newly created users start up with a working configuration. For existing users a small helper script is provided to create these files (see Create .gnupg home directories).

For internal purposes `gpg2` creates and maintains a few other files; They all live in the current home directory (see option --homedir). Only the `gpg2` program may modify these files.

`~/.gnupg`

  This is the default home directory which is used if neither the environment variable `GNUPGHOME` nor the option `--homedir` is given.

`~/.gnupg/pubring.gpg`

  The public keyring using a legacy format. You should backup this file.

  If this file is not available, `gpg` defaults to the new keybox format and creates a file `pubring.kbx` unless that file already exists in which case that file will also be used for OpenPGP keys.

  Note that in the case that both files, `pubring.gpg` and `pubring.kbx` exists but the latter has no OpenPGP keys, the legacy file `pubring.gpg` will be used. Take care: GnuPG versions before 2.1 will always use the file `pubring.gpg` because they do not know about the new keybox format. In the case that you have to use GnuPG 1.4 to decrypt archived data you should keep this file.

`~/.gnupg/pubring.gpg.lock`

  The lock file for the public keyring.

`~/.gnupg/pubring.kbx`

  The public keyring using the new keybox format. This file is shared with `gpgsm`. You should backup this file. See above for the relation between this file and it predecessor.

  To convert an existing `pubring.gpg` file to the keybox format, you first backup the ownertrust values, then rename `pubring.gpg` to `publickeys.backup`, so it won’t be recognized by any GnuPG version, run import, and finally restore the ownertrust values:

        $ cd ~/.gnupg
        $ gpg --export-ownertrust >otrust.lst
        $ mv pubring.gpg publickeys.backup
        $ gpg --import-options restore --import publickeys.backups
        $ gpg --import-ownertrust otrust.lst

`~/.gnupg/pubring.kbx.lock`

  The lock file for `pubring.kbx`.

`~/.gnupg/secring.gpg`

  The legacy secret keyring as used by GnuPG versions before 2.1. It is not used by GnuPG 2.1 and later. You may want to keep it in case you have to use GnuPG 1.4 to decrypt archived data.

`~/.gnupg/secring.gpg.lock`

  The lock file for the legacy secret keyring.

`~/.gnupg/.gpg-v21-migrated`

  File indicating that a migration to GnuPG 2.1 has been done.

`~/.gnupg/trustdb.gpg`

  The trust database. There is no need to backup this file; it is better to backup the ownertrust values (see option --export-ownertrust).

`~/.gnupg/trustdb.gpg.lock`

  The lock file for the trust database.

`~/.gnupg/random_seed`

  A file used to preserve the state of the internal random pool.

`~/.gnupg/openpgp-revocs.d/`

  This is the directory where gpg stores pre-generated revocation certificates. The file name corresponds to the OpenPGP fingerprint of the respective key. It is suggested to backup those certificates and if the primary private key is not stored on the disk to move them to an external storage device. Anyone who can access theses files is able to revoke the corresponding key. You may want to print them out. You should backup all files in this directory and take care to keep this backup closed away.

Operation is further controlled by a few environment variables:

HOME

  Used to locate the default home directory.

GNUPGHOME

  If set directory used instead of "~/.gnupg".

GPG_AGENT_INFO

  This variable is obsolete; it was used by GnuPG versions before 2.1.

PINENTRY_USER_DATA

  This value is passed via gpg-agent to pinentry. It is useful to convey extra information to a custom pinentry.

COLUMNS
LINES

  Used to size some displays to the full size of the screen.

LANGUAGE

  Apart from its use by GNU, it is used in the W32 version to override the language selection done through the Registry. If used and set to a valid and available language name (langid), the file with the translation is loaded from `gpgdir/gnupg.nls/langid.mo`. Here gpgdir is the directory out of which the gpg binary has been loaded. If it can’t be loaded the Registry is tried and as last resort the native Windows locale system is used.

When calling the gpg-agent component `gpg2` sends a set of environment variables to gpg-agent. The names of these variables can be listed using the command:

      gpg-connect-agent 'getinfo std_env_names' /bye | awk '$1=="D" {print $2}'

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