info gnupg

File: gnupg.info, Node: GPG Configuration Options, Next: GPG Key related Options, Up: GPG Options

4.2.1 How to change the configuration
-------------------------------------

These options are used to change the configuration and most of them are
usually found in the option file.

'--default-key NAME'
Use NAME as the default key to sign with. It is suggested to use a
fingerprint or at least a long keyID for NAME. If this option is
not used, the default key is the first key found in the secret
keyring. Note that '-u' or '--local-user' overrides this option.
This option may be given multiple times. In this case, the last
key for which a secret key is available is used. If there is no
secret key available for any of the specified values, GnuPG will
not emit an error message but continue as if this option wasn't
given.

'--default-recipient NAME'
Use NAME as default recipient if option '--recipient' is not used
and don't ask if this is a valid one. NAME must be non-empty and
it is suggested to use a fingerprint for NAME.

'--default-recipient-self'
Use the default key as default recipient if option '--recipient' is
not used and don't ask if this is a valid one. The default key is
the first one from the secret keyring or the one set with
'--default-key'.

'--no-default-recipient'
Reset '--default-recipient' and '--default-recipient-self'. Should
not be used in an option file.

'-v, --verbose'
Give more information during processing. If used twice, the input
data is listed in detail.

'--no-verbose'
Reset verbose level to 0. Should not be used in an option file.

'-q, --quiet'
Try to be as quiet as possible. Should not be used in an option
file.

'--batch'
'--no-batch'
Use batch mode. Never ask, do not allow interactive commands.
'--no-batch' disables this option. Note that even with a filename
given on the command line, gpg might still need to read from STDIN
(in particular if gpg figures that the input is a detached
signature and no data file has been specified). Thus if you do not
want to feed data via STDIN, you should connect STDIN to
'/dev/null'.

It is highly recommended to use this option along with the options
'--status-fd' and '--with-colons' for any unattended use of 'gpg'.
Should not be used in an option file.

'--no-tty'
Make sure that the TTY (terminal) is never used for any output.
This option is needed in some cases because GnuPG sometimes prints
warnings to the TTY even if '--batch' is used.

'--yes'
Assume "yes" on most questions. Should not be used in an option
file.

'--no'
Assume "no" on most questions. Should not be used in an option
file.

'--proc-all-sigs'
This option overrides the behaviour of the '--batch' option to stop
signature verification at the first bad signatures.

'--list-filter {select=EXPR}'
A list filter can be used to output only certain keys during key
listing commands. For the available property names, see the
description of '--import-filter'.

'--list-options PARAMETERS'
This is a space or comma delimited string that gives options used
when listing keys and signatures (that is, '--list-keys',
'--check-signatures', '--list-public-keys', '--list-secret-keys',
and the '--edit-key' functions). Options can be prepended with a
'no-' (after the two dashes) to give the opposite meaning. The
options are:

show-photos
Causes '--list-keys', '--check-signatures',
'--list-public-keys', and '--list-secret-keys' to display any
photo IDs attached to the key. Defaults to no. See also
'--photo-viewer'. Does not work with '--with-colons': see
'--attribute-fd' for the appropriate way to get photo data for
scripts and other frontends.

show-usage
Show usage information for keys and subkeys in the standard
key listing. This is a list of letters indicating the allowed
usage for a key ('E'=encryption, 'S'=signing,
'C'=certification, 'A'=authentication). Defaults to yes.

show-ownertrust
Show the ownertrust value for keys also in the standard key
listing. Defaults to no.

show-policy-urls
Show policy URLs in the '--check-signatures' listings.
Defaults to no.

show-notations
show-std-notations
show-user-notations
Show all, IETF standard, or user-defined signature notations
in the '--check-signatures' listings. Defaults to no.

show-keyserver-urls
Show any preferred keyserver URL in the '--check-signatures'
listings. Defaults to no.

show-uid-validity
Display the calculated validity of user IDs during key
listings. Defaults to yes.

show-unusable-uids
Show revoked and expired user IDs in key listings. Defaults
to no.

show-unusable-subkeys
Show revoked and expired subkeys in key listings. Defaults to
no.

show-unusable-sigs
Show key signature made using weak or unsupported algorithms.

show-keyring
Display the keyring name at the head of key listings to show
which keyring a given key resides on. Defaults to no.

show-sig-expire
Show signature expiration dates (if any) during
'--check-signatures' listings. Defaults to no.

show-sig-subpackets
Include signature subpackets in the key listing. This option
can take an optional argument list of the subpackets to list.
If no argument is passed, list all subpackets. Defaults to
no. This option is only meaningful when using '--with-colons'
along with '--check-signatures'.

show-only-fpr-mbox
For each user-id which has a valid mail address print only the
fingerprint followed by the mail address.

sort-sigs
With '--list-sigs' and '--check-sigs' sort the signatures by
keyID and creation time to make it easier to view the history
of these signatures. The self-signature is also listed before
other signatures. Defaults to yes. This option has no effect
in '-with-colons' mode.

'--verify-options PARAMETERS'
This is a space or comma delimited string that gives options used
when verifying signatures. Options can be prepended with a 'no-'
to give the opposite meaning. The options are:

show-photos
Display any photo IDs present on the key that issued the
signature. Defaults to no. See also '--photo-viewer'.

show-policy-urls
Show policy URLs in the signature being verified. Defaults to
yes.

show-notations
show-std-notations
show-user-notations
Show all, IETF standard, or user-defined signature notations
in the signature being verified. Defaults to IETF standard.

show-keyserver-urls
Show any preferred keyserver URL in the signature being
verified. Defaults to yes.

show-uid-validity
Display the calculated validity of the user IDs on the key
that issued the signature. Defaults to yes.

show-unusable-uids
Show revoked and expired user IDs during signature
verification. Defaults to no.

show-primary-uid-only
Show only the primary user ID during signature verification.
That is all the AKA lines as well as photo Ids are not shown
with the signature verification status.

'--enable-large-rsa'
'--disable-large-rsa'
With -generate-key and -batch, enable the creation of RSA secret
keys as large as 8192 bit. Note: 8192 bit is more than is
generally recommended. These large keys don't significantly
improve security, but they are more expensive to use, and their
signatures and certifications are larger. This option is only
available if the binary was build with large-secmem support.

'--enable-dsa2'
'--disable-dsa2'
Enable hash truncation for all DSA keys even for old DSA Keys up to
1024 bit. This is also the default with '--openpgp'. Note that
older versions of GnuPG also required this flag to allow the
generation of DSA larger than 1024 bit.

'--photo-viewer STRING'
This is the command line that should be run to view a photo ID.
"%i" will be expanded to a filename containing the photo. "%I"
does the same, except the file will not be deleted once the viewer
exits. Other flags are "%k" for the key ID, "%K" for the long key
ID, "%f" for the key fingerprint, "%t" for the extension of the
image type (e.g. "jpg"), "%T" for the MIME type of the image (e.g.
"image/jpeg"), "%v" for the single-character calculated validity of
the image being viewed (e.g. "f"), "%V" for the calculated
validity as a string (e.g. "full"), "%U" for a base32 encoded hash
of the user ID, and "%%" for an actual percent sign. If neither %i
or %I are present, then the photo will be supplied to the viewer on
standard input.

On Unix the default viewer is 'xloadimage -fork -quiet -title
'KeyID 0x%k' STDIN' with a fallback to 'display -title 'KeyID 0x%k'
%i' and finally to 'xdg-open %i'. On Windows '!ShellExecute 400
%i' is used; here the command is a meta command to use that API
call followed by a wait time in milliseconds which is used to give
the viewer time to read the temporary image file before gpg deletes
it again. Note that if your image viewer program is not secure,
then executing it from gpg does not make it secure.

'--exec-path STRING'
Sets a list of directories to search for photo viewers If not
provided photo viewers use the 'PATH' environment variable.

'--keyring FILE'
Add FILE to the current list of keyrings. If FILE begins with a
tilde and a slash, these are replaced by the $HOME directory. If
the filename does not contain a slash, it is assumed to be in the
GnuPG home directory ("~/.gnupg" unless '--homedir' or $GNUPGHOME
is used).

Note that this adds a keyring to the current list. If the intent
is to use the specified keyring alone, use '--keyring' along with
'--no-default-keyring'.

If the option '--no-keyring' has been used no keyrings will be used
at all.

Note that if the option 'use-keyboxd' is enabled in 'common.conf',
no keyrings are used at all and keys are all maintained by the
keyboxd process in its own database.

'--primary-keyring FILE'
This is a varian of '--keyring' and designates FILE as the primary
public keyring. This means that newly imported keys (via
'--import' or keyserver '--recv-from') will go to this keyring.

'--secret-keyring FILE'
This is an obsolete option and ignored. All secret keys are stored
in the 'private-keys-v1.d' directory below the GnuPG home
directory.

'--trustdb-name FILE'
Use FILE instead of the default trustdb. If FILE begins with a
tilde and a slash, these are replaced by the $HOME directory. If
the filename does not contain a slash, it is assumed to be in the
GnuPG home directory ('~/.gnupg' if '--homedir' or $GNUPGHOME is
not used).

'--homedir DIR'
Set the name of the home directory to DIR. If this option is not
used, the home directory defaults to '~/.gnupg'. It is only
recognized when given on the command line. It also overrides any
home directory stated through the environment variable 'GNUPGHOME'
or (on Windows systems) by means of the Registry entry
HKCU\SOFTWARE\GNU\GNUPG:HOMEDIR.

On Windows systems it is possible to install GnuPG as a portable
application. In this case only this command line option is
considered, all other ways to set a home directory are ignored.

'--display-charset NAME'
Set the name of the native character set. This is used to convert
some informational strings like user IDs to the proper UTF-8
encoding. Note that this has nothing to do with the character set
of data to be encrypted or signed; GnuPG does not recode
user-supplied data. If this option is not used, the default
character set is determined from the current locale. A verbosity
level of 3 shows the chosen set. This option should not be used on
Windows. Valid values for NAME are:

iso-8859-1
This is the Latin 1 set.

iso-8859-2
The Latin 2 set.

iso-8859-15
This is currently an alias for the Latin 1 set.

koi8-r
The usual Russian set (RFC-1489).

utf-8
Bypass all translations and assume that the OS uses native
UTF-8 encoding.

'--utf8-strings'
'--no-utf8-strings'
Assume that command line arguments are given as UTF-8 strings. The
default ('--no-utf8-strings') is to assume that arguments are
encoded in the character set as specified by '--display-charset'.
These options affect all following arguments. Both options may be
used multiple times. This option should not be used in an option
file.

This option has no effect on Windows. There the internal used
UTF-8 encoding is translated for console input and output. The
command line arguments are expected as Unicode and translated to
UTF-8. Thus when calling this program from another, make sure to
use the Unicode version of CreateProcess.

'--options FILE'
Read options from FILE and do not try to read them from the default
options file in the homedir (see '--homedir'). This option is
ignored if used in an options file.

'--no-options'
Shortcut for '--options /dev/null'. This option is detected before
an attempt to open an option file. Using this option will also
prevent the creation of a '~/.gnupg' homedir.

'-z N'
'--compress-level N'
'--bzip2-compress-level N'
'--no-compress'
Set compression level to N for the ZIP and ZLIB compression
algorithms. The default is to use the default compression level of
zlib (normally 6). '--bzip2-compress-level' sets the compression
level for the BZIP2 compression algorithm (defaulting to 6 as
well). This is a different option from '--compress-level' since
BZIP2 uses a significant amount of memory for each additional
compression level.

Option '-z' sets both. A value of 0 for N disables compression. A
value of -1 forces compression using the default level. Option
'--no-compress' is identical to '-z0'.

Except for the '--store' command compression is always used unless
'gpg' detects that the input is already compressed. To inhibit the
use of compression use '-z0' or '--no-compress'; to force
compression use '-z-1' or option 'z' with another compression level
than the default as indicated by -1. Note that this overriding of
the default deection works only with 'z' and not with the long
variant of this option.

'--bzip2-decompress-lowmem'
Use a different decompression method for BZIP2 compressed files.
This alternate method uses a bit more than half the memory, but
also runs at half the speed. This is useful under extreme low
memory circumstances when the file was originally compressed at a
high '--bzip2-compress-level'.

'--mangle-dos-filenames'
'--no-mangle-dos-filenames'
Older version of Windows cannot handle filenames with more than one
dot. '--mangle-dos-filenames' causes GnuPG to replace (rather than
add to) the extension of an output filename to avoid this problem.
This option is off by default and has no effect on non-Windows
platforms.

'--ask-cert-level'
'--no-ask-cert-level'
When making a key signature, prompt for a certification level. If
this option is not specified, the certification level used is set
via '--default-cert-level'. See '--default-cert-level' for
information on the specific levels and how they are used.
'--no-ask-cert-level' disables this option. This option defaults
to no.

'--default-cert-level N'
The default to use for the check level when signing a key.

0 means you make no particular claim as to how carefully you
verified the key.

1 means you believe the key is owned by the person who claims to
own it but you could not, or did not verify the key at all. This
is useful for a "persona" verification, where you sign the key of a
pseudonymous user.

2 means you did casual verification of the key. For example, this
could mean that you verified the key fingerprint and checked the
user ID on the key against a photo ID.

3 means you did extensive verification of the key. For example,
this could mean that you verified the key fingerprint with the
owner of the key in person, and that you checked, by means of a
hard to forge document with a photo ID (such as a passport) that
the name of the key owner matches the name in the user ID on the
key, and finally that you verified (by exchange of email) that the
email address on the key belongs to the key owner.

Note that the examples given above for levels 2 and 3 are just
that: examples. In the end, it is up to you to decide just what
"casual" and "extensive" mean to you.

This option defaults to 0 (no particular claim).

'--min-cert-level'
When building the trust database, treat any signatures with a
certification level below this as invalid. Defaults to 2, which
disregards level 1 signatures. Note that level 0 "no particular
claim" signatures are always accepted.

'--trusted-key LONG KEY ID OR FINGERPRINT'
Assume that the specified key (which should be given as
fingerprint) is as trustworthy as one of your own secret keys.
This option is useful if you don't want to keep your secret keys
(or one of them) online but still want to be able to check the
validity of a given recipient's or signator's key. If the given
key is not locally available but an LDAP keyserver is configured
the missing key is imported from that server. The value "none" is
explicitly allowed to distinguish between the use of any
trusted-key option and no use of this option at all (e.g. due to
the '--no-options' option).

'--add-desig-revoker [sensitive:]FINGERPRINT'
Add the key specified by FINGERPRINT as a designated revoker to
newly created keys. If the fingerprint is prefixed with the
keyword "sensitive:" that info is normally not exported with the
key. This option may be given several times to add more than one
designated revoker. If the keyword "clear" is used instead of a
fingerprint, all previously fiven fingerprints are discarded.
Designated revokers are marked on the key as non-revocable. Note
that a designated revoker specified using a parameter file will
also be added to the key.

'--default-new-key-adsk FINGERPRINT'
Add the subkey specified by FINGERPRINT as an Additional Decryption
Subkey (ADSK) to newly created keys. This option may be given
several time to add more than one ADSK. It is also possible to give
several fingerprints delimited by space or comma as value to this
option. If the keyword "clear" is used instead of a fingerprint,
all previously specified fingerprints are discarded (useful to
override options given in a config file). The fingerprint is
expected to specify a subkey and it does not need an exclamation
mark as suffix; it must be given in cmpact format (40 or 64
hex-digits without any spaces).

'--trust-model {pgp|classic|tofu|tofu+pgp|direct|always|auto}'
Set what trust model GnuPG should follow. The models are:

pgp
This is the Web of Trust combined with trust signatures as
used in PGP 5.x and later. This is the default trust model
when creating a new trust database.

classic
This is the standard Web of Trust as introduced by PGP 2.

tofu
TOFU stands for Trust On First Use. In this experimental
trust model, the first time a key is seen, it is memorized.
If later another key with a user id with the same email
address is seen, both keys are marked as suspect. In that
case, the next time either is used, a warning is displayed
describing the conflict, why it might have occurred (either
the user generated a new key and failed to cross sign the old
and new keys, the key is forgery, or a man-in-the-middle
attack is being attempted), and the user is prompted to
manually confirm the validity of the key in question.

Because a potential attacker is able to control the email
address and thereby circumvent the conflict detection
algorithm by using an email address that is similar in
appearance to a trusted email address, whenever a message is
verified, statistics about the number of messages signed with
the key are shown. In this way, a user can easily identify
attacks using fake keys for regular correspondents.

When compared with the Web of Trust, TOFU offers significantly
weaker security guarantees. In particular, TOFU only helps
ensure consistency (that is, that the binding between a key
and email address doesn't change). A major advantage of TOFU
is that it requires little maintenance to use correctly. To
use the web of trust properly, you need to actively sign keys
and mark users as trusted introducers. This is a
time-consuming process and anecdotal evidence suggests that
even security-conscious users rarely take the time to do this
thoroughly and instead rely on an ad-hoc TOFU process.

In the TOFU model, policies are associated with bindings
between keys and email addresses (which are extracted from
user ids and normalized). There are five policies, which can
be set manually using the '--tofu-policy' option. The default
policy can be set using the '--tofu-default-policy' option.

The TOFU policies are: 'auto', 'good', 'unknown', 'bad' and
'ask'. The 'auto' policy is used by default (unless
overridden by '--tofu-default-policy') and marks a binding as
marginally trusted. The 'good', 'unknown' and 'bad' policies
mark a binding as fully trusted, as having unknown trust or as
having trust never, respectively. The 'unknown' policy is
useful for just using TOFU to detect conflicts, but to never
assign positive trust to a binding. The final policy, 'ask'
prompts the user to indicate the binding's trust. If batch
mode is enabled (or input is inappropriate in the context),
then the user is not prompted and the 'undefined' trust level
is returned.

tofu+pgp
This experimental trust model combines TOFU with the Web of
Trust. This is done by computing the trust level for each
model and then taking the maximum trust level where the trust
levels are ordered as follows: 'unknown < undefined < marginal
< fully < ultimate < expired < never'.

By setting '--tofu-default-policy=unknown', this model can be
used to implement the web of trust with TOFU's conflict
detection algorithm, but without its assignment of positive
trust values, which some security-conscious users don't like.

direct
Key validity is set directly by the user and not calculated
via the Web of Trust. This model is solely based on the key
and does not distinguish user IDs. Note that when changing to
another trust model the trust values assigned to a key are
transformed into ownertrust values, which also indicate how
you trust the owner of the key to sign other keys.

always
Skip key validation and assume that used keys are always fully
valid. You generally won't use this unless you are using some
external validation scheme. This option also suppresses the
"[uncertain]" tag printed with signature checks when there is
no evidence that the user ID is bound to the key. Note that
this trust model still does not allow the use of expired,
revoked, or disabled keys.

auto
Select the trust model depending on whatever the internal
trust database says. This is the default model if such a
database already exists. Note that a tofu trust model is not
considered here and must be enabled explicitly.

'--always-trust'
Identical to '--trust-model always'.

'--assert-signer FPR_OR_FILE'
This option checks whether at least one valid signature on a file
has been made with the specified key. The key is either specified
as a fingerprint or a file listing fingerprints. The fingerprint
must be given or listed in compact format (no colons or spaces in
between). This option can be given multiple times and each
fingerprint is checked against the signing key as well as the
corresponding primary key. If FPR_OR_FILE specifies a file, empty
lines are ignored as well as all lines starting with a hash sign.
With this option gpg is guaranteed to return with an exit code of 0
if and only if a signature has been encountered, is valid, and the
key matches one of the fingerprints given by this option.

'--assert-pubkey-algo ALGOLIST'
During data signature verification this options checks whether the
used public key algorithm matches the algorithms given by ALGOLIST.
This option can be given multiple times to concatenate more
algorithms to the list; the delimiter of the list are either commas
or spaces.

The algorithm names given in the list may either be verbatim names
like "ed25519" with an optional leading single equal sign, or being
prefixed with ">", ">=", "<=", or "<". That prefix operator is
applied to the number part of the algorithm name; for example 2048
in "rsa2048" or 384 in "brainpoolP384r1". If the the leading
non-digits in the name matches, the prefix operator is used to
compare the number part, a trailing suffix is ignored in this case.
For example an algorithm list ">rsa3000, >=brainpool384r1,
=ed25519" allows RSA signatures with more that 3000 bits, Brainpool
curves 384 and 512, and the ed25519 algorithm.

With this option gpg (and also gpgv) is guaranteed to return with
an exit code of 0 if and only if all valid signatures on data are
made using a matching algorithm from the given list.

'--auto-key-locate MECHANISMS'
'--no-auto-key-locate'
GnuPG can automatically locate and retrieve keys as needed using
this option. This happens when encrypting to an email address (in
the "user@example.com" form), and there are no "user@example.com"
keys on the local keyring. This option takes any number of the
mechanisms listed below, in the order they are to be tried.
Instead of listing the mechanisms as comma delimited arguments, the
option may also be given several times to add more mechanism. The
option '--no-auto-key-locate' or the mechanism "clear" resets the
list. The default is "local,wkd".

cert
Locate a key using DNS CERT, as specified in RFC-4398.

dane
Locate a key using DANE, as specified in
draft-ietf-dane-openpgpkey-05.txt.

wkd
Locate a key using the Web Key Directory protocol.

ldap
Locate the key using the configured LDAP servers. This method
is similar to the 'keyserver' mechanism but always uses only
LDAP servers.

ntds
Locate the key using the Active Directory (Windows only).
This method also allows one to search by fingerprint using the
command '--locate-external-key'. Note that this mechanism is
actually a shortcut for the mechanism 'ldap' using only
"ldap:///" as the keyserver.

keyserver
Locate a key using a keyserver. This method also allows one
to search by fingerprint using the command
'--locate-external-key' if any of the configured keyservers is
an LDAP server.

keyserver-URL
In addition, a keyserver URL as used in the 'dirmngr'
configuration may be used here to query that particular
keyserver. This method also allows one to search by
fingerprint using the command '--locate-external-key' if the
URL specifies an LDAP server.

local
Locate the key using the local keyrings. This mechanism
allows the user to select the order a local key lookup is
done. Thus using '--auto-key-locate local' is identical to
'--no-auto-key-locate'.

nodefault
This flag disables the standard local key lookup, done before
any of the mechanisms defined by the '--auto-key-locate' are
tried. The position of this mechanism in the list does not
matter. It is not required if 'local' is also used.

clear
Clear all defined mechanisms. This is useful to override
mechanisms given in a config file. Note that a 'nodefault' in
MECHANISMS will also be cleared unless it is given after the
'clear'.

'--auto-key-import'
'--no-auto-key-import'
This is an offline mechanism to get a missing key for signature
verification and for later encryption to this key. If this option
is enabled and a signature includes an embedded key, that key is
used to verify the signature and on verification success the key is
imported. The default is '--no-auto-key-import'.

On the sender (signing) site the option '--include-key-block' needs
to be used to put the public part of the signing key as “Key Block
subpacket” into the signature.

'--auto-key-retrieve'
'--no-auto-key-retrieve'
These options enable or disable the automatic retrieving of keys
from a keyserver when verifying signatures made by keys that are
not on the local keyring. The default is '--no-auto-key-retrieve'.

The order of methods tried to lookup the key is:

1. If the option '--auto-key-import' is set and the signatures
includes an embedded key, that key is used to verify the signature
and on verification success that key is imported.

2. If a preferred keyserver is specified in the signature and the
option 'honor-keyserver-url' is active (which is not the default),
that keyserver is tried. Note that the creator of the signature
uses the option '--sig-keyserver-url' to specify the preferred
keyserver for data signatures.

3. If the signature has the Signer's UID set (e.g. using
'--sender' while creating the signature) a Web Key Directory (WKD)
lookup is done. This is the default configuration but can be
disabled by removing WKD from the auto-key-locate list or by using
the option '--disable-signer-uid'.

4. If any keyserver is configured and the Issuer Fingerprint is
part of the signature (since GnuPG 2.1.16), the configured
keyservers are tried.

Note that this option makes a "web bug" like behavior possible.
Keyserver or Web Key Directory operators can see which keys you
request, so by sending you a message signed by a brand new key
(which you naturally will not have on your local keyring), the
operator can tell both your IP address and the time when you
verified the signature.

'--keyid-format {none|short|0xshort|long|0xlong}'
Select how to display key IDs. "none" does not show the key ID at
all but shows the fingerprint in a separate line. "short" is the
traditional 8-character key ID. "long" is the more accurate (but
less convenient) 16-character key ID. Add an "0x" to either to
include an "0x" at the beginning of the key ID, as in 0x99242560.
Note that this option is ignored if the option '--with-colons' is
used.

'--keyserver NAME'
This option is deprecated - please use the '--keyserver' in
'dirmngr.conf' instead.

Use NAME as your keyserver. This is the server that
'--receive-keys', '--send-keys', and '--search-keys' will
communicate with to receive keys from, send keys to, and search for
keys on. The format of the NAME is a URI:
'scheme:[//]keyservername[:port]' The scheme is the type of
keyserver: "hkp"/"hkps" for the HTTP (or compatible) keyservers or
"ldap"/"ldaps" for the LDAP keyservers. Note that your particular
installation of GnuPG may have other keyserver types available as
well. Keyserver schemes are case-insensitive.

Most keyservers synchronize with each other, so there is generally
no need to send keys to more than one server. The keyserver
'hkp://keys.gnupg.net' uses round robin DNS to give a different
keyserver each time you use it.

'--keyserver-options {NAME=VALUE}'
This is a space or comma delimited string that gives options for
the keyserver. Options can be prefixed with a 'no-' to give the
opposite meaning. Valid import-options or export-options may be
used here as well to apply to importing ('--recv-key') or exporting
('--send-key') a key from a keyserver. While not all options are
available for all keyserver types, some common options are:

include-revoked
When searching for a key with '--search-keys', include keys
that are marked on the keyserver as revoked. Note that not
all keyservers differentiate between revoked and unrevoked
keys, and for such keyservers this option is meaningless.
Note also that most keyservers do not have cryptographic
verification of key revocations, and so turning this option
off may result in skipping keys that are incorrectly marked as
revoked.

include-disabled
When searching for a key with '--search-keys', include keys
that are marked on the keyserver as disabled. Note that this
option is not used with HKP keyservers.

auto-key-retrieve
This is an obsolete alias for the option 'auto-key-retrieve'.
Please do not use it; it will be removed in future versions..

honor-keyserver-url
When using '--refresh-keys', if the key in question has a
preferred keyserver URL, then use that preferred keyserver to
refresh the key from. In addition, if auto-key-retrieve is
set, and the signature being verified has a preferred
keyserver URL, then use that preferred keyserver to fetch the
key from. Note that this option introduces a "web bug": The
creator of the key can see when the keys is refreshed. Thus
this option is not enabled by default.

include-subkeys
When receiving a key, include subkeys as potential targets.
Note that this option is not used with HKP keyservers, as they
do not support retrieving keys by subkey id.

only-pubkeys
Do now allow to import secret keys.

timeout
http-proxy=VALUE
verbose
debug
check-cert
ca-cert-file
These options have no more function since GnuPG 2.1. Use the
'dirmngr' configuration options instead.

The default list of options is: "self-sigs-only, import-clean,
repair-keys, repair-pks-subkey-bug, export-attributes". However,
if the actual used source is an LDAP server "no-self-sigs-only" is
assumed unless "self-sigs-only" has been explicitly configured.

'--completes-needed N'
Number of completely trusted users to introduce a new key signer
(defaults to 1).

'--marginals-needed N'
Number of marginally trusted users to introduce a new key signer
(defaults to 3)

'--tofu-default-policy {auto|good|unknown|bad|ask}'
The default TOFU policy (defaults to 'auto'). For more information
about the meaning of this option, *note trust-model-tofu::.

'--max-cert-depth N'
Maximum depth of a certification chain (default is 5).

'--no-sig-cache'
Do not cache the verification status of key signatures. Caching
gives a much better performance in key listings. However, if you
suspect that your public keyring is not safe against write
modifications, you can use this option to disable the caching. It
probably does not make sense to disable it because all kind of
damage can be done if someone else has write access to your public
keyring.

'--auto-check-trustdb'
'--no-auto-check-trustdb'
If GnuPG feels that its information about the Web of Trust has to
be updated, it automatically runs the '--check-trustdb' command
internally. This may be a time consuming process.
'--no-auto-check-trustdb' disables this option.

'--use-agent'
'--no-use-agent'
This is dummy option. 'gpg' always requires the agent.

'--gpg-agent-info'
This is dummy option. It has no effect when used with 'gpg'.

'--agent-program FILE'
Specify an agent program to be used for secret key operations. The
default value is determined by running 'gpgconf' with the option
'--list-dirs'. Note that the pipe symbol ('|') is used for a
regression test suite hack and may thus not be used in the file
name.

'--dirmngr-program FILE'
Specify a dirmngr program to be used for keyserver access. The
default value is '/usr/local/bin/dirmngr'.

'--disable-dirmngr'
Entirely disable the use of the Dirmngr.

'--no-autostart'
Do not start the gpg-agent or the dirmngr if it has not yet been
started and its service is required. This option is mostly useful
on machines where the connection to gpg-agent has been redirected
to another machines. If dirmngr is required on the remote machine,
it may be started manually using 'gpgconf --launch dirmngr'.

'--lock-once'
Lock the databases the first time a lock is requested and do not
release the lock until the process terminates.

'--lock-multiple'
Release the locks every time a lock is no longer needed. Use this
to override a previous '--lock-once' from a config file.

'--lock-never'
Disable locking entirely. This option should be used only in very
special environments, where it can be assured that only one process
is accessing those files. A bootable floppy with a stand-alone
encryption system will probably use this. Improper usage of this
option may lead to data and key corruption.

'--exit-on-status-write-error'
This option will cause write errors on the status FD to immediately
terminate the process. That should in fact be the default but it
never worked this way and thus we need an option to enable this, so
that the change won't break applications which close their end of a
status fd connected pipe too early. Using this option along with
'--enable-progress-filter' may be used to cleanly cancel long
running gpg operations.

'--limit-card-insert-tries N'
With N greater than 0 the number of prompts asking to insert a
smartcard gets limited to N-1. Thus with a value of 1 gpg won't at
all ask to insert a card if none has been inserted at startup.
This option is useful in the configuration file in case an
application does not know about the smartcard support and waits ad
infinitum for an inserted card.

'--no-random-seed-file'
GnuPG uses a file to store its internal random pool over
invocations. This makes random generation faster; however
sometimes write operations are not desired. This option can be
used to achieve that with the cost of slower random generation.

'--no-greeting'
Suppress the initial copyright message.

'--no-secmem-warning'
Suppress the warning about "using insecure memory".

'--no-permission-warning'
Suppress the warning about unsafe file and home directory
('--homedir') permissions. Note that the permission checks that
GnuPG performs are not intended to be authoritative, but rather
they simply warn about certain common permission problems. Do not
assume that the lack of a warning means that your system is secure.

Note that the warning for unsafe '--homedir' permissions cannot be
suppressed in the gpg.conf file, as this would allow an attacker to
place an unsafe gpg.conf file in place, and use this file to
suppress warnings about itself. The '--homedir' permissions
warning may only be suppressed on the command line.

'--require-secmem'
'--no-require-secmem'
Refuse to run if GnuPG cannot get secure memory. Defaults to no
(i.e. run, but give a warning).

'--require-cross-certification'
'--no-require-cross-certification'
When verifying a signature made from a subkey, ensure that the
cross certification "back signature" on the subkey is present and
valid. This protects against a subtle attack against subkeys that
can sign. Defaults to '--require-cross-certification' for 'gpg'.

'--expert'
'--no-expert'
Allow the user to do certain nonsensical or "silly" things like
signing an expired or revoked key, or certain potentially
incompatible things like generating unusual key types. This also
disables certain warning messages about potentially incompatible
actions. As the name implies, this option is for experts only. If
you don't fully understand the implications of what it allows you
to do, leave this off. '--no-expert' disables this option.