I want two way data sync between two `CentOS` based servers, so I installed `Unison` on both of my `CentOS` servers. I made a script file on root which runs unison and works fine, and syncs the files, when I run it from terminal. When I put that script in the crontab the sync simply does not work.
My `/etc/crontab` is 

```
*/1  *  *  *  * root sh /root/syncaaa.sh &>/root/unison-cron.log

```

And what crontab puts in the `/root/unison-cron.log`

```
Usage: unison [options]
    or unison root1 root2 [options]
    or unison profilename [options]

For a list of options, type "unison -help".
For a tutorial on basic usage, type "unison -doc tutorial".
For other documentation, type "unison -doc topics".

```

My unison.log file does not updated when run via cron, but only updates when runs directly via terminal. I checked in cron logs and syncaaa.sh file runs every miunte.
Can anyone suggest me what I should do to debug it?

> 
> Note: My server 1 can login to server 2 without password, as I have
>  set rsa keys in server2 authorized\_keys.
> 
> 
> 

**> Update 1:** I tried `set -x` in the script and it printed

```
+ chmod -R 0777 /home/user11/folder/
+ /usr/bin/unison
Usage: unison [options]
    or unison root1 root2 [options]
    or unison profilename [options]

For a list of options, type "unison -help".
For a tutorial on basic usage, type "unison -doc tutorial".
For other documentation, type "unison -doc topics"

```

and `/usr/bin/unison` command works fine on terminal