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 [ -hklQqV ] [ --clear --confhost --gpg2 --help --ignore-missing --list
       --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 easily 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. Typically, private key
       files are specified by filename only, without path, although it is possible to specify an absolute or
       relative path to the private key file as well. If just a private key filename is used, which is typical
       usage, keychain will look for the specified private key files in ~/.ssh, ~/.ssh2, or with the
       -c/--confhost option, inspect the ~/.ssh/config file and use the IdentityFile option to determine the
       location of the private key. Private keys can be symlinks to the actual private key.

       Keychain expects associated public key files to exist in the same directory as the private key files,
       with a .pub extension.  If the private key is a symlink, the public key can be found alongside the
       symlink, or in the same directory as the symlink target (This capability requires the 'readlink' command
       to be available on the system.)

       As an additional feature, if a private key has an extension ".ext", keychain will look for
       privkey.ext.pub first, and if not found, will look for privkey.pub.

       Keychain also supports gpg-agent in the same ways that ssh-agent is supported.  By default keychain
       attempts to start ssh-agent only.  You can modify this behavior 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 start ssh-agent if it is found in your path. 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.

--confhost
By default, keychain will look for key pairs in the ~/.ssh/ directory. The --confhost option will
inform keychain to look in ~/.ssh/config for IdentityFile settings defined for particular hosts, and
use these paths to locate keys.

--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).

--absolute
Any arguments to "--dir" are interpreted to be absolute. The default behavior is to append
"/.keychain" to the argument for backwards compatibility.

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

--query
Keychain will print lines in KEY=value format representing the values which are set by the agents.

--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.

--gpg2
This option changes the default gpg calls to use gpg2 instead to support distributions such as Ubuntu
which has both gpg and gpg2

-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.

-l --list
List signatures of all active SSH keys, and exit, similar to "ssh-add -l".

-L --list-fp
List fingerprints of all active SSH keys, and exit, similar to "ssh-add -L".

--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 highlighting 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 ones 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.

--systemd
Inject environment variables into the systemd --user session.

-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
Allows a timeout to be set for identities added to ssh-agent. When this option is used with a
keychain invocation that starts ssh-agent itself, then keychain uses the appropriate ssh-agent option
to set the default timeout for ssh-agent. The --timeout option also gets passed to ssh-add
invocations, so any keys added to a running ssh-agent will be individually configured to have the
timeout specified, overriding any ssh-agent default.

Most users can simply use the timeout setting they desire and get the result they want -- with all
identities having the specified timeout, whether added by keychain or not. More advanced users can
use one invocation of keychain to set the default timeout, and optionally set different timeouts for
keys added by using a subsequent invocation of keychain.

-V --version
Show version information.

EXAMPLES

       This snippet should work in most shells to load two ssh keys and one gpg key:

           eval `keychain --eval id_rsa id_dsa 0123ABCD`

       For the fish shell, use the following format:

           if status --is-interactive
               keychain --eval --quiet -Q id_rsa | source
           end

       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