我正在使用以下方式更改文件权限
chmod a+w /var/run/btsync.debconf-default.pid
并且成功了。重启后我得到：
service btsync start
* Autostarting btsync instance 'debconf-default'
start-stop-daemon: unable to open pidfile '/var/run/btsync.debconf-default.pid' for writing (Permission denied)
* Failed to start btsync instance debconf-default - please check the configuration file /etc/btsync/debconf-default.conf
还尝试使用 root / sudo 等。我做错了什么？