cmd/run, doc/toolbox-run: Add flag --no-tty/-T to run command.

Summary:
VSCode remote SSH extension needs to run commands inside toolbox without
a TTY, otherwise it fails. With this patch, vscode can connect to
toolbox in a remote host if you put `RemoteCommand toolbox run -T bash`
in ssh config; it should work as well if using `authorized_keys`
instead. The naming of `-T` option is borrowed from `ssh -T`.

containers#587

doc/toolbox-run.1.md

@@ -5,7 +5,8 @@ toolbox\-run - Run a command in an existing toolbox container
 
 ## SYNOPSIS
 **toolbox run** [*--container NAME* | *-c NAME*]
-            [*--release RELEASE* | *-r RELEASE*] [*COMMAND*]
+            [*--release RELEASE* | *-r RELEASE*]
+            [*--no-tty* | *-T*] [*COMMAND*]
 
 ## DESCRIPTION
 
@@ -34,6 +35,10 @@ or entirely customized containers created from custom-built base images.
 Run command inside a toolbox container for a different operating system
 RELEASE than the host.
 
+**--no-tty**, **-T**
+
+Don't allocate pseudo-TTY.
+
 ## EXAMPLES
 
 ### Run ls inside a toolbox container using the default image matching the host OS

src/cmd/run.go

@@ -34,6 +34,7 @@ var (
 	runFlags struct {
 		container string
 		release   string
+		noTty     bool
 	}
 )
 
@@ -59,6 +60,12 @@ func init() {
 		"",
 		"Run command inside a toolbox container for a different operating system release than the host.")
 
+	flags.BoolVarP(&runFlags.noTty,
+		"no-tty",
+		"T",
+		false,
+		"Run command without allocating a pseudo-TTY.")
+
 	runCmd.SetHelpFunc(runHelp)
 	rootCmd.AddCommand(runCmd)
 }
@@ -290,11 +297,14 @@ func runCommand(container string,
 
 	execArgs = append(execArgs, []string{
 		"--interactive",
-		"--tty",
 		"--user", currentUser.Username,
 		"--workdir", workingDirectory,
 	}...)
 
+	if !runFlags.noTty {
+		execArgs = append(execArgs, "--tty")
+	}
+
 	execArgs = append(execArgs, envOptions...)
 
 	execArgs = append(execArgs, []string{

toolbox

@@ -71,6 +71,7 @@ toolbox_container_prefix_default=""
 toolbox_image=""
 toolbox_runtime_directory="$XDG_RUNTIME_DIR"/toolbox
 user_id_real=$(id -ru 2>&3)
+tty=true
 verbose=false
 
 
@@ -1582,13 +1583,17 @@ run()
 
     $emit_escape_sequence && printf "\033]777;container;push;%s;toolbox\033\\" "$toolbox_container"
 
+    extra_podman_args=()
+    if "$tty"; then
+        extra_podman_args+=(--tty)
+    fi
     # shellcheck disable=SC2016
     # for the command passed to capsh
     # shellcheck disable=SC2086
     $podman_command exec \
             --interactive \
-            --tty \
             --user "$USER" \
+            "${extra_podman_args[@]}" \
             --workdir "$PWD" \
             $set_environment \
             "$toolbox_container" \
@@ -2611,6 +2616,9 @@ case $op in
                     exit_if_non_positive_argument --release "$arg"
                     release=$arg
                     ;;
+                -T | --no-tty )
+                    tty=false
+                    ;;
                 * )
                     exit_if_unrecognized_option "$1"
             esac