Thanks all to respond my query. Actully i m using POSIX thread in C and Linux. I got the solution by doing some thing here and there. The answer is :
To terminate a user thread prematurely use the API "pthread_cancel" from the thread which want to kill the target thread.
For the furthre details about pthread library follw the following link :
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http://publib.boulder.ibm.com/iserie...s/users_97.htm
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hanks all.