#!/bin/sh
#### ssh-find-agent --- connect to an existing ssh agent, or start one
#### Jim Blandy <jimb@red-bean.com> --- May 2000

#### The command
####
####      eval `ssh-find-agent`
####
#### puts you in touch with an SSH authentication agent.  The only
#### difference between this and the ordinary ssh-agent command is
#### that ssh-find-agent tries to find an existing ssh agent, whereas
#### ssh-agent always starts a new one.
####
#### If we're already in touch with an SSH agent, don't print anything.

progname="$(basename $0)"

### Are we already in touch with an agent?
if ssh-add -l > /dev/null 2>&1; then
  exit 0
fi

### Try to get in touch with the last agent we talked to.
contact="/tmp/last-ssh-agent-$USER"
if [ -f "$contact" ]; then
  source "$contact" > /dev/null
  if ssh-add -l > /dev/null 2>&1; then
    cat "$contact"
    exit 0
  fi
fi

### Start a new agent, and save its contact info.
[ ! -f "$contact" -o -w "$contact" ] || {
  echo "$progname: can't write agent info file: $contact" >&2
  exit 1
}
ssh-agent > "$contact" || {
  echo "$progname: couldn't start agent" >&2
  exit 1
}
source "$contact" > /dev/null || {
  echo "$progname: error reading new agent contact file: $contact" >&2
  exit 1
}

### Verify that we are indeed in contact with the new agent.
ssh-add -l > /dev/null || {
  echo "$progname: started new agent, but couldn't connect to it" >&2
  exit 1
}

### Spit out the new contact info.
cat "$contact"