[snip] > So what happens if a program with a DCB open for INPUT performs a > fork()? Does fork() leave a blank space where the DCB was? What > happens if the child performs a READ? Something ought to fail > because the parent may have scratched the data set and the child > would be reading unallocated DASD tracks. Repeat the question > with OUTPUT in place of INPUT. If the parent has a descriptor of > a UNIX file, the child inherits it with no problem: the disk > blocks are not freed until some process unlinks the file and > both the parent and child close it. (But what if YA process > opens it with O_TRUNC?) > > -- gil
IIRC, the z/OS control structures associated with legacy I/O (DEBs, etc) are not propogated to the child. Now, the DCB is "copied" (like it's in the program or in STORAGE OBTAIN'ed memory in key 8), but the associated DEB is not. So if the child does any I/O using the DCB, it will fail with some sort of error (don't know what, haven't tried). The O_TRUNC option applied when the UNIX file is opened. The child gets an already opened file descriptor. So the file is not opened a second time, so the O_TRUNC is not done. -- John McKown Senior Systems Programmer HealthMarkets Keeping the Promise of Affordable Coverage Administrative Services Group Information Technology The information contained in this e-mail message may be privileged and/or confidential. It is for intended addressee(s) only. If you are not the intended recipient, you are hereby notified that any disclosure, reproduction, distribution or other use of this communication is strictly prohibited and could, in certain circumstances, be a criminal offense. If you have received this e-mail in error, please notify the sender by reply and delete this message without copying or disclosing it. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
