2.2 Option Summary

--options file

Reads configuration from file instead of from the default per-user configuration file. The default configuration file is named gpg-agent.conf and expected in the .gnupg directory directly below the home directory of the user.

--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 W32 systems) by means of the Registry entry HKCU\Software\GNU\GnuPG:HomeDir.

-v

--verbose

Outputs additional information while running. You can increase the verbosity by giving several verbose commands to gpgsm, such as ‘-vv’.

-q

--quiet

Try to be as quiet as possible.

--batch

Don’t invoke a pinentry or do any other thing requiring human interaction.

--faked-system-time epoch

This option is only useful for testing; it sets the system time back or forth to epoch which is the number of seconds elapsed since the year 1970.

--debug-level level

Select the debug level for investigating problems. level may be a numeric value or a keyword:

none

No debugging at all. A value of less than 1 may be used instead of the keyword.

basic

Some basic debug messages. A value between 1 and 2 may be used instead of the keyword.

advanced

More verbose debug messages. A value between 3 and 5 may be used instead of the keyword.

expert

Even more detailed messages. A value between 6 and 8 may be used instead of the keyword.

guru

All of the debug messages you can get. A value greater than 8 may be used instead of the keyword. The creation of hash tracing files is only enabled if the keyword is used.

How these messages are mapped to the actual debugging flags is not specified and may change with newer releases of this program. They are however carefully selected to best aid in debugging.

--debug flags

This option is only useful for debugging and the behaviour may change at any time without notice. FLAGS are bit encoded and may be given in usual C-Syntax. The currently defined bits are:

0 (1)

X.509 or OpenPGP protocol related data

1 (2)

values of big number integers

2 (4)

low level crypto operations

5 (32)

memory allocation

6 (64)

caching

7 (128)

show memory statistics.

9 (512)

write hashed data to files named dbgmd-000*

10 (1024)

trace Assuan protocol

12 (4096)

bypass all certificate validation

--debug-all

Same as --debug=0xffffffff

--debug-wait n

When running in server mode, wait n seconds before entering the actual processing loop and print the pid. This gives time to attach a debugger.

--no-detach

Don’t detach the process from the console. This is mainly useful for debugging.

-s

--sh

-c

--csh

Format the info output in daemon mode for use with the standard Bourne shell or the C-shell respectively. The default is to guess it based on the environment variable SHELL which is correct in almost all cases.

--write-env-file file

Often it is required to connect to the agent from a process not being an inferior of gpg-agent and thus the environment variable with the socket name is not available. To help setting up those variables in other sessions, this option may be used to write the information into file. If file is not specified the default name ${HOME}/.gpg-agent-info will be used. The format is suitable to be evaluated by a Bourne shell like in this simple example:

eval $(cat file)
eval $(cut -d= -f 1 < file | xargs echo export)

--no-grab

Tell the pinentry not to grab the keyboard and mouse. This option should in general not be used to avoid X-sniffing attacks.

--log-file file

Append all logging output to file. This is very helpful in seeing what the agent actually does. If neither a log file nor a log file descriptor has been set on a Windows platform, the Registry entry HKCU\Software\GNU\GnuPG:DefaultLogFile, if set, is used to specify the logging output.

--allow-mark-trusted

Allow clients to mark keys as trusted, i.e. put them into the trustlist.txt file. This is by default not allowed to make it harder for users to inadvertently accept Root-CA keys.

--no-allow-external-cache

Tell Pinentry not to enable features which use an external cache for passphrases.

Some desktop environments prefer to unlock all credentials with one master password and may have installed a Pinentry which employs an additional external cache to implement such a policy. By using this option the Pinentry is advised not to make use of such a cache and instead always ask the user for the requested passphrase.

--ignore-cache-for-signing

This option will let gpg-agent bypass the passphrase cache for all signing operation. Note that there is also a per-session option to control this behaviour but this command line option takes precedence.

--default-cache-ttl n

Set the time a cache entry is valid to n seconds. The default is 600 seconds.

--default-cache-ttl-ssh n

Set the time a cache entry used for SSH keys is valid to n seconds. The default is 1800 seconds.

--max-cache-ttl n

Set the maximum time a cache entry is valid to n seconds. After this time a cache entry will be expired even if it has been accessed recently or has been set using gpg-preset-passphrase. The default is 2 hours (7200 seconds).

--max-cache-ttl-ssh n

Set the maximum time a cache entry used for SSH keys is valid to n seconds. After this time a cache entry will be expired even if it has been accessed recently or has been set using gpg-preset-passphrase. The default is 2 hours (7200 seconds).

--enforce-passphrase-constraints

Enforce the passphrase constraints by not allowing the user to bypass them using the “Take it anyway” button.

--min-passphrase-len n

Set the minimal length of a passphrase. When entering a new passphrase shorter than this value a warning will be displayed. Defaults to 8.

--min-passphrase-nonalpha n

Set the minimal number of digits or special characters required in a passphrase. When entering a new passphrase with less than this number of digits or special characters a warning will be displayed. Defaults to 1.

--check-passphrase-pattern file

Check the passphrase against the pattern given in file. When entering a new passphrase matching one of these pattern a warning will be displayed. file should be an absolute filename. The default is not to use any pattern file.

Security note: It is known that checking a passphrase against a list of pattern or even against a complete dictionary is not very effective to enforce good passphrases. Users will soon figure up ways to bypass such a policy. A better policy is to educate users on good security behavior and optionally to run a passphrase cracker regularly on all users passphrases to catch the very simple ones.

--max-passphrase-days n

Ask the user to change the passphrase if n days have passed since the last change. With --enforce-passphrase-constraints set the user may not bypass this check.

--enable-passphrase-history

This option does nothing yet.

--pinentry-program filename

Use program filename as the PIN entry. The default is installation dependent.

--pinentry-touch-file filename

By default the filename of the socket gpg-agent is listening for requests is passed to Pinentry, so that it can touch that file before exiting (it does this only in curses mode). This option changes the file passed to Pinentry to filename. The special name /dev/null may be used to completely disable this feature. Note that Pinentry will not create that file, it will only change the modification and access time.

--scdaemon-program filename

Use program filename as the Smartcard daemon. The default is installation dependent and can be shown with the gpgconf command.

--disable-scdaemon

Do not make use of the scdaemon tool. This option has the effect of disabling the ability to do smartcard operations. Note, that enabling this option at runtime does not kill an already forked scdaemon.

--use-standard-socket

--no-use-standard-socket

By enabling this option gpg-agent will listen on the socket named S.gpg-agent, located in the home directory, and not create a random socket below a temporary directory. Tools connecting to gpg-agent should first try to connect to the socket given in environment variable GPG_AGENT_INFO and then fall back to this socket. This option may not be used if the home directory is mounted on a remote file system which does not support special files like fifos or sockets. Note, that --use-standard-socket is the default on Windows systems. The default may be changed at build time. It is possible to test at runtime whether the agent has been configured for use with the standard socket by issuing the command gpg-agent --use-standard-socket-p which returns success if the standard socket option has been enabled.

--display string

--ttyname string

--ttytype string

--lc-ctype string

--lc-messages string

--xauthority string

These options are used with the server mode to pass localization information.

--keep-tty

--keep-display

Ignore requests to change the current tty or X window system’s DISPLAY variable respectively. This is useful to lock the pinentry to pop up at the tty or display you started the agent.

--enable-ssh-support

Enable the OpenSSH Agent protocol.

In this mode of operation, the agent does not only implement the gpg-agent protocol, but also the agent protocol used by OpenSSH (through a separate socket). Consequently, it should be possible to use the gpg-agent as a drop-in replacement for the well known ssh-agent.

SSH Keys, which are to be used through the agent, need to be added to the gpg-agent initially through the ssh-add utility. When a key is added, ssh-add will ask for the password of the provided key file and send the unprotected key material to the agent; this causes the gpg-agent to ask for a passphrase, which is to be used for encrypting the newly received key and storing it in a gpg-agent specific directory.

Once a key has been added to the gpg-agent this way, the gpg-agent will be ready to use the key.

Note: in case the gpg-agent receives a signature request, the user might need to be prompted for a passphrase, which is necessary for decrypting the stored key. Since the ssh-agent protocol does not contain a mechanism for telling the agent on which display/terminal it is running, gpg-agent’s ssh-support will use the TTY or X display where gpg-agent has been started. To switch this display to the current one, the following command may be used:

gpg-connect-agent updatestartuptty /bye

Although all GnuPG components try to start the gpg-agent as needed, this is not possible for the ssh support because ssh does not know about it. Thus if no GnuPG tool which accesses the agent has been run, there is no guarantee that ssh is abale to use gpg-agent for authentication. To fix this you may start gpg-agent if needed using this simple command:

gpg-connect-agent /bye

Adding the --verbose shows the progress of starting the agent.

All the long options may also be given in the configuration file after stripping off the two leading dashes.