Script to reattach a shell to SSH

start-ssh-agent

#!/bin/sh

# this script knows how to look in /tmp/ssh-* for SSH agent sockets.
# These are created by the SSH agent, or for hosts you connected to
# with 'ssh -A' (or you set 'ForwardAgent yes' in your .ssh/config).

# the upshot is that if *any* of your current ssh connections have an
# agent connection, then you can run this script and it will set your
# environment variables up in the shell you are currently working in.

# Finally, if it doesn't find any agents at all then it will start a
# new one.

# you might like to make this available via a shell alias, and put it
# in your .bash_profile or another similar location.  If you pass "-q"
# as the first argument, it will not print anything.  For instance,
# put it in your ~/bin, and then add to your .bashrc:

#   Q=-q; [ -t ] && Q=; . bin/start-ssh-agent $Q
#   alias ssha='. ~/bin/start-ssh-agent'

# Note, if the agent on the end of the socket has crashed/hung then
# the login shell may hang.  You can usually press Ctrl+C to skip the
# rest of the script at that point and then 'killall ssh-agent'

if [ "$1" = "-q" ]
then
	QUIET=1
	shift
fi

PATTERN=$1
[ -z "$PATTERN" ] && PATTERN=:

OLD_SSH_AUTH_SOCK="$SSH_AUTH_SOCK"
SSH_AUTH_SOCK=

if [ -d "`ls -d /tmp/ssh-* 2>/dev/null | head -1`" ]
then
    for x in "$OLD_SSH_AUTH_SOCK" /tmp/ssh-*/*
    do
	#echo -n Checking $x ...
	[ -S $x ] || continue #( echo not a socket, ignoring; continue )
	export SSH_AUTH_SOCK=$x
	if [ -n "`ssh-add -l 2>/dev/null | grep \"$PATTERN\"`" ]
	then
	    #echo that\'ll do!
	    found="$x"
            break
	#else
	    #echo no relevant identities, next!
	fi
    done
    if [ -z "$found" ]
    then
        for x in "$OLD_SSH_AUTH_SOCK" /tmp/ssh-*/*
        do
	    #echo -n Checking $x ...
	    [ -S $x ] || continue #( echo not a socket, ignoring; continue )
	    export SSH_AUTH_SOCK=$x
	    if [ -n "$(ssh-add -l 2>&1 | grep -i 'no identities')" ]
	    then
	         found="$x"
 		 break
	    fi
        done
    fi
fi

if [ -z "$SSH_AUTH_SOCK" ]
then
    #echo Starting a new agent, as \$SSH_AUTH_SOCK is \""$SSH_AUTH_SOCK"\"
    eval $(ssh-agent -s 2>/dev/null)
fi

export SSH_AUTH_SOCK SSH_AGENT_PID

if [ -z "$QUIET" ]
then
	echo "SSH_AUTH_SOCK is $SSH_AUTH_SOCK"
	ssh-add -l
fi