README: add example bash function for shell wrapping

README.md

@@ -1,2 +1,69 @@
 # docker-images
 various builds for docker images
+
+
+## building
+
+```bash
+make
+```
+
+## bash functions
+
+These `*-dev` images are primarily used as shell wrappers for testing on
+various linuxes.
+
+```bash
+function fedora() {
+  if [ ${#SSH_AUTH_SOCK} -gt 0 ] ; then
+    local vsock="-v $SSH_AUTH_SOCK:$SSH_AUTH_SOCK"
+  fi
+  if [ ${#XAUTHORITY} -gt 0 ] ; then
+    local vxauth="-v $XAUTHORITY:$XAUTHORITY"
+  fi
+  docker run \
+    --rm \
+    -i -t \
+    --hostname=$(hostname -s)-fedora \
+    -v $HOME:$HOME \
+    ${vxauth} \
+    -v /tmp/.ICE-unix/:/tmp/.ICE-unix/ \
+    ${vsock} \
+    -v /var/run/docker.sock:/var/run/docker.sock \
+    -v /usr/bin/docker:/usr/bin/docker:ro \
+    --env HOME \
+    --env XAUTHORITY \
+    --env SESSION_MANAGER \
+    --env DISPLAY \
+    --user $USER \
+    --env SSH_AUTH_SOCK \
+    --env PATH=/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin \
+    --privileged \
+    --workdir $(pwd) \
+    ${1+"$@"} \
+    docker.usersys/${USER}/fedora-dev
+}
+
+function ubuntu() {
+  if [ ${#SSH_AUTH_SOCK} -gt 0 ] ; then
+    local sock="-v $SSH_AUTH_SOCK:$SSH_AUTH_SOCK"
+  fi
+  docker run \
+    --rm \
+    -i -t \
+    --hostname=$(hostname -s)-ubuntu \
+    -v $HOME:$HOME \
+    ${sock} \
+    -v /var/run/docker.sock:/var/run/docker.sock \
+    -v /usr/bin/docker:/usr/bin/docker:ro \
+    --env HOME \
+    --user $USER \
+    --env SSH_AUTH_SOCK \
+    --env PATH=/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin \
+    --privileged \
+    -w $(pwd) \
+    ${1+"$@"} \
+    docker.usersys/${USER}/ubuntu-dev
+}
+
+```