Unfortunately this is not possible. Can you please describe your usage scenario? Maybe we can find some other approaches.

I have to send the value of a certain variable on server Z from server X.The result of certain variable which is being computed on server X needs to be send to server Z.On server Z this variable is under the configuration A>B.

The restful API approach can be used to address this issue:

If I do not want to create a job which will change the value of variable and I trigger that job from other server using rest api.
Isnt there any rest api which can change tha variable value.
As I checked below is the way of changing
Retrieve full xml representation of configuration root/test into a temp file using below command: curl -u admin:admin http://localhost:8810/rest/configurations/ > tempfile.xml
Here needs to be replaced with query result of first step.

3.Edit tempfile.xml and change the description property to desired value (or add description element if it does not exist).
4.Post back modified content using below command: curl -X POST -u admin:admin --data-binary "@tempfile.xml" http://localhost:8810/rest/configurations

Can we know any direct rest api to change value of a variable instead of fetching full xml and editing and then reposting it.

Currently no, you may submit an improvement request at track.pmease.com