Ubuntu Manpage: keychain - re-use ssh-agent and/or gpg-agent between logins

NAME

       keychain - re-use ssh-agent and/or gpg-agent between logins

SYNOPSIS

       keychain [ -hkQqV ] [ --clear --help --ignore-missing --noask
       --nocolor --nogui --nolock --quick --quiet --version ]
       [ --agents list ] [ --attempts num ] [ --dir dirname ] [ --host name ] [ --lockwait seconds ]
       [ --stop which ] [ --timeout minutes ] [ keys... ]

DESCRIPTION

       keychain is a manager for ssh-agent, typically run from ~/.bash_profile.  It allows your shells and cron
       jobs to share a single ssh-agent process.  By default, the ssh-agent started by keychain is long-running
       and will continue to run, even after you have logged out from the system.  If you want to change this
       behavior, take a look at the --clear and --timeout options, described below.

       When keychain is run, it checks for a running ssh-agent, otherwise it starts one.  It saves the ssh-agent
       environment variables to ~/.keychain/${HOSTNAME}-sh, so that subsequent logins and non-interactive shells
       such as cron jobs can source the file and make passwordless ssh connections.  In addition, when keychain
       runs, it verifies that the key files specified on the command-line are known to ssh-agent, otherwise it
       loads them, prompting you for a password if necessary.

       Keychain also supports gpg-agent in the same ways that ssh-agent is supported.  By default keychain
       attempts to start all available agents but will fall back to only gpg-agent or only ssh-agent if either
       is unavailable.  You can specifically limit keychain using the --agents option.

       keychain supports most UNIX-like operating systems, including Cygwin.  It works with Bourne-compatible,
       csh-compatible and fish shells.

OPTIONS

--agents list
Start the agents listed. By default keychain will build the list automatically based on the
existence of ssh-agent and/or gpg-agent on the system. The list should be comma-separated, for
example "gpg,ssh"

--attempts num
Try num times to add keys before giving up. The default is 1.

--clear
Delete all of ssh-agent's keys. Typically this is used in .bash_profile. The theory behind this is
that keychain should assume that you are an intruder until proven otherwise. However, while this
option increases security, it still allows your cron jobs to use your ssh keys when you're logged
out.

--confirm
Keys are subject to interactive confirmation by the SSH_ASKPASS program before being used for
authentication. See the -c option for ssh-add(1).

--dir dirname
Keychain will use dirname rather than $HOME/.keychain

--eval
Keychain will print lines to be evaluated in the shell on stdout. It respects the SHELL environment
variable to determine if Bourne shell or C shell output is expected.

--env filename
After parsing options, keychain will load additional environment settings from "filename". By
default, if "--env" is not given, then keychain will attempt to load from ~/.keychain/[hostname]-env
or alternatively ~/.keychain/env. The purpose of this file is to override settings such as PATH, in
case ssh is stored in a non-standard place.

-h --help
Show help that looks remarkably like this man-page. As of 2.6.10, help is sent to stdout so it can be
easily piped to a pager.

--host name
Set alternate hostname for creation of pidfiles

--ignore-missing
Don't warn if some keys on the command-line can't be found. This is useful for situations where you
have a shared .bash_profile, but your keys might not be available on every machine where keychain is
run.

--inherit which
Attempt to inherit agent variables from the environment. This can be useful in a variety of
circumstances, for example when ssh-agent is started by gdm. The following values are valid for
"which":

local Inherit when a pid (e.g. SSH_AGENT_PID) is set in the environment. This disallows
inheriting a forwarded agent.

any Inherit when a sock (e.g. SSH_AUTH_SOCK) is set in the environment. This allows
inheriting a forwarded agent.

local-once Same as "local", but only inherit if keychain isn't already providing an agent.

any-once Same as "any", but only inherit if keychain isn't already providing an agent.

By default, keychain-2.5.0 and later will behave as if "--inherit local-once" is specified. You
should specify "--noinherit" if you want the older behavior.

--lockwait seconds
How long to wait for the lock to become available. Defaults to 5 seconds. Specify a value of zero or
more. If the lock cannot be acquired within the specified number of seconds, then this keychain
process will forcefully acquire the lock.

--noask
This option tells keychain do everything it normally does (ensure ssh-agent is running, set up the
~/.keychain/[hostname]-{c}sh files) except that it will not prompt you to add any of the keys you
specified if they haven't yet been added to ssh-agent.

--nocolor
Disable color hilighting for non ANSI-compatible terms.

--nogui
Don't honor SSH_ASKPASS, if it is set. This will cause ssh-add to prompt on the terminal instead of
using a graphical program.

--noinherit
Don't inherit any agent processes, overriding the default "--inherit local-once"

--nolock
Don't attempt to use a lockfile while manipulating files, pids and keys.

-k --stop which
Kill currently running agent processes. The following values are valid for "which":

all Kill all agent processes and quit keychain immediately. Prior to keychain-2.5.0, this was
the behavior of the bare "--stop" option.

others Kill agent processes other than the one keychain is providing. Prior to keychain-2.5.0,
keychain would do this automatically. The new behavior requires that you specify it
explicitly if you want it.

mine Kill keychain's agent processes, leaving other agents alone.

-Q --quick
If an ssh-agent process is running then use it. Don't verify the list of keys, other than making
sure it's non-empty. This option avoids locking when possible so that multiple terminals can be
opened simultaneously without waiting on each other.

-q --quiet
Only print messages in case of warning, error or required interactivity. As of version 2.6.10, this
also suppresses "Identities added" messages for ssh-agent.

--timeout minutes
Set a timeout in minutes on your keys. This is conveyed to ssh-agent which does the actual timing
out of keys since keychain doesn't run continuously.

-V --version
Show version information.

EXAMPLES

       This snippet should work in any shell to load two ssh keys and one gpg key:

           eval `keychain --eval id_rsa id_dsa 0123ABCD`

       If you have trouble with that in csh:

           setenv SHELL /bin/csh
           eval `keychain --eval id_rsa id_dsa 0123ABCD`

       This is equivalent for Bourne shells (including bash and zsh) but doesn't use keychain's --eval feature:

           keychain id_rsa id_dsa 0123ABCD
           [ -z "$HOSTNAME" ] && HOSTNAME=`uname -n`
           [ -f $HOME/.keychain/$HOSTNAME-sh ] && \
                   . $HOME/.keychain/$HOSTNAME-sh
           [ -f $HOME/.keychain/$HOSTNAME-sh-gpg ] && \
                   . $HOME/.keychain/$HOSTNAME-sh-gpg

       This is equivalent for C shell (including tcsh):

           keychain id_rsa id_dsa 0123ABCD
           host=`uname -n`
           if (-f $HOME/.keychain/$host-csh) then
                   source $HOME/.keychain/$host-csh
           endif
           if (-f $HOME/.keychain/$host-csh-gpg) then
                   source $HOME/.keychain/$host-csh-gpg
           endif

       To load keychain variables from a script (for example from cron) and abort unless id_dsa is available:

           # Load keychain variables and check for id_dsa
           [ -z "$HOSTNAME" ] && HOSTNAME=`uname -n`
           . $HOME/.keychain/$HOSTNAME-sh 2>/dev/null
           ssh-add -l 2>/dev/null | grep -q id_dsa || exit 1

NOTES