zshrc: piv-agent now can re-use agents

.zshrc2

@@ -113,21 +113,41 @@ fi
 gbes() { git for-each-ref --sort=-committerdate refs/heads refs/remotes --format="%(authordate:format:%y-%m-%d.%a %H:%M %z)|%(color:red)%(objectname:short)|%(color:yellow)%(refname:short)%(color:reset)|%(color:reset)%(authorname): %(color:green)%(subject)" --color=always | column -ts"|" | less -FX }
 piv-agent()
 {
-    eval $(ssh-agent -k)
+    local agent_file="/tmp/piv-agent-$(whoami)"
+    if [[ -f $agent_file ]]; then
+        source $agent_file
+    fi
     # they are: ubuntu, macos, respectively
     local SO_PATHS=( "/usr/lib64/opensc-pkcs11.so" "/usr/local/lib/opensc-pkcs11.so" )
-    for i in ${SO_PATHS[*]}; do
-        if [[ -f "$i" ]]; then
-            echo "using: $i"
-            eval $(ssh-agent -P "$i")
-            ssh-add -s "$i"
-            echo "now available keys:"
-            ssh-add -l
-            return 0
+    local SO_FILE
+    for SO_FILE in ${SO_PATHS[*]}; do
+        if [[ -f "$SO_FILE" ]]; then
+            break
         fi
     done
-    echo "opensc-pkcs11.so not found"
-    return 1
+    if [[ ! -f "$SO_FILE" ]]; then
+        echo "error: opensc-pkcs11.so not found"
+        return 1
+    fi
+    if ! ps -p "$SSH_AGENT_PID" > /dev/null; then
+        echo "launch agent using: $SO_FILE"
+        ret=$(ssh-agent -P "$SO_FILE")
+        echo "$ret" > $agent_file
+        eval "$ret"
+        if ! ps -p $SSH_AGENT_PID > /dev/null; then
+            echo "failed to launch agent"
+            return 1
+        fi
+    else
+        echo "using existing agent: $SSH_AGENT_PID"
+    fi
+    if ! ssh-add -l > /dev/null; then
+        echo "no keys found in this agent, let's add some"
+        ssh-add -s "$SO_FILE"
+    fi
+    pgrep ssh-agent | grep -v $SSH_AGENT_PID | xargs kill -9
+    echo "now available keys:"
+    ssh-add -l
 }
 
 # key bindings