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Difference between null file and empty file

 
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darcatty

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Joined: 03 Mar 2009
Posts: 5
Location: Chennai

PostPosted: Wed Apr 29, 2009 5:40 pm    Post subject: Difference between null file and empty file
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In my proc... one step is executing to create a null file is as follows

Step1 exec pgm=IEFBR14
dd1 dd dsn= ' .......... ' , disp=(new, catlg, del), ......... NULLFILE

here ,

What is the meaning for null file?
Will the file contains records after executing the above step1.

Also... pls explain abt the difference between null file and empty file?

Thanks
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Robert Sample

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Joined: 06 Jun 2008
Posts: 8217
Location: Dubuque, Iowa, USA

PostPosted: Wed Apr 29, 2009 5:47 pm    Post subject:
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DSN=NULLFILE is a dummy data set. If you read from it you get end of file immediately. If you write to it, the data goes to the bit bucket immediately, so is lost forever.

An empty file may or may not get end of file immediately if you read from it (that depends on whether the file has been opened for output already or not). Data written to an empty file will be stored in the file and be available later.
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