octocat · July 3, 2014 19:33 · Jul 3, 2014
diff --git a/ssh_key_add.sh b/ssh_key_add.sh
@@ -0,0 +1,52 @@
+# Note: ~/.ssh/environment should not be used, as it
+#       already has a different purpose in SSH.
+
+env=~/.ssh/agent.env
+
+# Note: Don't bother checking SSH_AGENT_PID. It's not used
+#       by SSH itself, and it might even be incorrect
+#       (for example, when using agent-forwarding over SSH).
+
+agent_is_running() {
+    if [ "$SSH_AUTH_SOCK" ]; then
+        # ssh-add returns:
+        #   0 = agent running, has keys
+        #   1 = agent running, no keys
+        #   2 = agent not running
+        # if your keys are not stored in ~/.ssh/id_rsa.pub or ~/.ssh/id_dsa.pub, you'll need
+        # to paste the proper path after ssh-add
+        ssh-add -l >/dev/null 2>&1 || [ $? -eq 1 ]
+    else
+        false
+    fi
+}
+
+agent_has_keys() {
+    # if your keys are not stored in ~/.ssh/id_rsa.pub or ~/.ssh/id_dsa.pub, you'll need
+    # to paste the proper path after ssh-add
+    ssh-add -l >/dev/null 2>&1
+}
+
+agent_load_env() {
+    . "$env" >/dev/null
+}
+
+agent_start() {
+    (umask 077; ssh-agent >"$env")
+    . "$env" >/dev/null
+}
+
+if ! agent_is_running; then
+    agent_load_env
+fi
+
+# if your keys are not stored in ~/.ssh/id_rsa.pub or ~/.ssh/id_dsa.pub, you'll need
+# to paste the proper path after ssh-add
+if ! agent_is_running; then
+    agent_start
+    ssh-add
+elif ! agent_has_keys; then
+    ssh-add
+fi
+
+unset env