By simple meaning a contract is an agreement enforceable by law. As such any condition attached to a contract which is not enforceable by law will make the contract voidable or even void. An agreement with an employee wherein the employer says that the employee will not get any claim for permanency of employment is not maintainable by law and, therefore, it is void. However, if the job itself is temporary, that is due to be completed within a fixed period, then it is implied that the employee and employer relationship will cease to exist when the fixed period for which the job is given is over or when the job is finished. In that case, termination of employment or the legal relationship will come to an end automatically.
Regards,
Madhu.T.K