use Perl

The Problem

I use Screen to leave programs running and an SSH key agent to shell between machines and use CVS without reentering my password. Disconnnecting from the server that the screen session is running on removes the connection to the SSH agent.

What should happen:

• I should be able to run a command, say latestssh, to reattach my current SSH agent to the screen window
• New screen windows should pick up on the new agent immediately

The Solution

A shell snippet (Zsh, but easily portable):

local agentdir=~/.latestssh
local agentfile=$agentdir/$HOST.sh
mkdir -p $agentdir
chmod 0700 $agentdir >/dev/null

if [ -n "$SSH_AUTH_SOCK" -a -z $STY ]; then
    echo "export SSH_AUTH_SOCK=$SSH_AUTH_SOCK" >$agentfile
    chmod 0600 $agentfile >/dev/null
fi

# ...existing windows can run this alias
alias latestssh="source $agentfile; ls \$SSH_AUTH_SOCK"

# ...new windows get it automatically
if [ -n "$STY" ]; then
    source $agentfile
fi