dbuild: run interactive shell by default

If not given any other args to run, just run an interactive shell.

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Message-Id: <20190909113140.9130-1-bhalevy@scylladb.com>

tools/toolchain/dbuild

@@ -11,7 +11,10 @@ done
 
 interactive=
 
-if [[ "$1" = -* ]]; then
+if [[ $# -eq 0 ]]; then
+    interactive=y
+    docker_args=(-it)
+elif [[ "$1" = -* ]]; then
     while [[ "$1" != "--" && $# != 0 ]]; do
 	case "$1" in
 	    --*)
@@ -37,6 +40,12 @@ if [[ "$1" = -* ]]; then
     shift
 fi
 
+if [[ $# != 0 ]]; then
+    args=("$@")
+else
+    args=(/bin/bash -i)
+fi
+
 MAVEN_LOCAL_REPO="$HOME/.m2"
 
 mkdir -p "$MAVEN_LOCAL_REPO"
@@ -56,7 +65,7 @@ docker_common_args=(
        -w "$PWD" \
        "${docker_args[@]}" \
        "$(<"$here/image")" \
-       "$@"
+       "${args[@]}"
 )
 
 if [[ -n "$interactive" ]]; then