Create attach-bash-to-running-container.md

Author: simonw

docker/attach-bash-to-running-container.md

@@ -0,0 +1,13 @@
+# Attaching a bash shell to a running Docker container
+
+Use `docker ps` to find the container ID:
+
+    $ docker ps                        
+    CONTAINER ID        IMAGE                        COMMAND                  CREATED             STATUS              PORTS               NAMES
+    81b2ad3194cb        alexdebrie/livegrep-base:1   "/livegrep-github-re…"   2 minutes ago       Up 2 minutes                            compassionate_yalow
+
+Run `docker exec -it ID bash` to start a bash session in that container:
+
+    $ docker exec -it 81b2ad3194cb bash
+
+I made the mistake of using `docker attach 81b2ad3194cb` first, which attaches you to the command running as CMD in that conatiner, and means that if you hit `Ctrl+C` you exit that command and terminate the container!