I am trying to configure lsyncd to synchronize a folder on the home page of the logged user but when I try to capture the value of his `$HOME` with `os.getenv("HOME")` the result is always

> 
> Error prepare /etc/lsyncd/lsyncd.conf.lua: /etc/lsyncd/lsyncd.conf.lua: 14: attempt to concatenate a nil value
> 
> 
> 

I tried `os.getenv("PWD")` and it runs without displaying errors but it doesn't work and in the `/var/log/lsyncd/lsyncd.status` file I see that it tries to use the `/.mozilla/firefox` address as if PWD were empty. 

I tried to keep the environment variables by running the command `sudo -E service lsyncd restart` and modifying sudoers with `Defaults env_keep +="HOME"`, all in vain.  

Any ideas? 

I enclose my code:

```
settings{
    logfile = "/var/log/lsyncd/lsyncd.log",
    statusFile = "/var/log/lsyncd/lsyncd.status",
}

sync{
        default.rsync,
        source =  os.getenv("HOME").."/.mozilla/firefox/",
        target =  "tmp/.mozilla/firefox/",
        delay  = 1,
}

```