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 both Bourne-compatible and csh-compatible shells.
OPTIONS
"--agents
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
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.
"--dir
Keychain will use dirname rather than $HOME/.keychain
"-h
Show help that looks remarkably like this man-page.
"--host
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
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
How long to wait for the lock to become available. Defaults to 30
seconds.
"--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
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
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
Only print messages in case of warning, error or required
interactivity.
"--timeout
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
Show version information.
EXAMPLES
This snippet would work in .bash_profile (for bash) or .zlogin (for
zsh) to load two ssh keys and one gpg key:
keychain id_rsa id_dsa 0123ABCD
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
This snippet would work in .login for csh:
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
Keychain is maintained by Aron Griffis <agriffis@gentoo.org>. If you
need to report a bug or request an enhancement, please do so at
<http://bugs.gentoo.org/> and assign to agriffis@gentoo.org
Keychain was originally written by Daniel Robbins
<drobbins@gentoo.org>, who has also written a series of three articles
about it. The articles can be found starting at
<http://www-106.ibm.com/developerworks/library/l-keyc.html>
