Allow pipe + redirect in task/run stanzas, exec() in /bin/sh

This patch extends the capabilities of task and run .conf stanzas by
enabling pipes and redirects.

Example:

    task [s] echo "foo" | cat >/tmp/bar
    run  [s] echo "$HOME" >/tmp/secret

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

src/exec.c

@@ -213,6 +213,27 @@ int run_interactive(char *cmd, char *fmt, ...)
 	return status;
 }
 
+int exec_runtask(char *cmd, char *args[])
+{
+	size_t i;
+	char buf[1024] = "";
+	char *argv[4] = {
+		"sh",
+		"-c",
+		buf,
+		NULL
+	};
+
+	for (i = 0; args[i]; i++) {
+		strlcat(buf, args[i], sizeof(buf));
+		if (args[i + 1])
+			strlcat(buf, " ", sizeof(buf));
+	}
+	logit(LOG_DEBUG, "Calling %s %s", _PATH_BSHELL, buf);
+
+	return execve(_PATH_BSHELL, argv, __environ);
+}
+
 static void prepare_tty(char *tty, char *procname, int console)
 {
 	/* Reset signal handlers that were set by the parent process */