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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 his 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 on 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 one of:
none
no debugging at all.
basic
some basic debug messages
advanced
more verbose debug messages
expert
even more detailed messages
guru
all of the debug messages you can get

How these messages are mapped to the actual debugging flags is not specified and may change with newer releaes 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 manly usefule for debugging.
-s
--sh
-c
--csh
Format the info output in daemon mode for use with the standard Bourne shell respective the C-shell . The default is to guess it based on the environment variable SHELL which is in almost all cases sufficient.
--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 pinentryo not to grab the keyboard and mouse. This option should in general not be used to avaoid X-sniffing attacks.
--log-file file
Append all logging output to file. This is very helpful in seeing what the agent actually does.


--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 inadvertly accept Root-CA keys.
--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 are 600 seconds.
--default-cache-ttl-ssh n
Set the time a cache entry used for SSH keys is valid to n seconds. The default are 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 get expired even if it has been accessed recently. The default are 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 get expired even if it has been accessed recently. The default are 2 hours (7200 seconds).
--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.
--pinentry-program filename
Use program filename as the PIN entry. The default is installation dependend and can be shown with the --version command.
--pinentry-touch-file filename
By default the file name 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 dependend and can be shown with the --version 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 the fall back to this socket. This option may not be used if the home directory is mounted as a remote file system.

Note, that as of now, W32 systems default to this option.

--display string
--ttyname string
--ttytype string
--lc-type string
--lc-messages string
These options are used with the server mode to pass localization information.
--keep-tty
--keep-display
Ignore requests to change change the current tty respective the X window system's DISPLAY variable. This is useful to lock the pinentry to pop up at the tty or display you started the agent.


--enable-ssh-support
Enable emulation of 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 seperate socket). Consequently, it should 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 follwing command may be used:

          echo UPDATESTARTUPTTY | gpg-connect-agent
     

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