dosh: add warning comment about shebang option

dosh

@@ -15,6 +15,10 @@ then
 	exec "$0" "$@"
 elif [ "$__" != "/bin/bash" ] && [ "$__" = "$2" ]
 then
+	# Warning: Splitting the single shebang argument into many is not
+	#          portable! Please consider using env(1) instead:
+	#
+	#              #!/usr/bin/env -S dosh [ARGS...]
 	read -r -a args <<<"$1"
 	shift
 	exec <"$1"

examples/shebang-env.dosh

@@ -0,0 +1,10 @@
+#!/usr/bin/env -S dosh --dockerfile Dockerfile.fedora
+#
+# Copyright (c) 2024 Gaël PORTAY
+#
+# SPDX-License-Identifier: MIT
+#
+
+whoami
+echo "$USER" "$0" "$#" "$@"
+cat /etc/os*release

tests.bash

@@ -517,6 +517,16 @@ else
 fi
 echo
 
+run "Test shebang using env"
+if examples/shebang-env.dosh | tee /dev/stderr | \
+   grep -q 'PRETTY_NAME="Fedora 25 (Twenty Five)'
+then
+	ok
+else
+	ko
+fi
+echo
+
 run "Test options --detach and --exec"
 if container="$(dosh --detach)" && \
    dosh "$@" --exec "$container"  -c "hostname" | tee /dev/stderr | \