dssh: add the option to set (or not set) a controlling terminal.

Basically, we want ssh's behavior, where the command will "just do the
right thing" based on whether it is being run interactively or not.

diff --git a/dssh b/dssh
index 710fdac..7540c8b 100755 (executable)
--- a/dssh
+++ b/dssh
@@ -19,16 +19,25 @@ options:
 -h:           show this help message.
 -i [ID]:      ssh into a docker node with this container ID
 -n [name]:    ssh into a docker node with this name
+-t [0 or 1]:  0 to avoid allocating a TTY; 1 to allocate one.
+              The default will be set based on whether this appears
+              to be an interactive shell.
 EOF
 }
 
 DOCKER_IMAGE_ID=""
 DOCKER_IMAGE_NAME=""
-while getopts  "hi:n:" flag; do
+if [ -t 0 ]; then
+    ALLOCATE_TTY=1
+else
+    ALLOCATE_TTY=0
+fi
+while getopts  "hi:n:t:" flag; do
     case $flag in
     h) usage; exit 0;;
     i) DOCKER_IMAGE_ID=${OPTARG};;
     n) DOCKER_IMAGE_NAME=${OPTARG};;
+    t) ALLOCATE_TTY=${OPTARG};;
     *) echo "getopts error"
         echo
         usage
@@ -41,6 +50,10 @@ if [ $# -eq 0 ]; then
 else
     RUN_COMMAND="${@}"
 fi
+EXTRA_DOCKER_ARGS=""
+if [ ${ALLOCATE_TTY} -ne 0 ]; then
+    EXTRA_DOCKER_ARGS="${EXTRA_DOCKER_ARGS} -t"
+fi
 
 which docker &>/dev/null || die "docker must be on the PATH."
 
@@ -61,4 +74,4 @@ else
         die "failed to find a docker image named ${DOCKER_IMAGE_NAME}"
 fi
 
-docker exec -it "${DOCKER_IMAGE_ID}" ${RUN_COMMAND}
+docker exec -i ${EXTRA_DOCKER_ARGS} "${DOCKER_IMAGE_ID}" ${RUN_COMMAND}