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From: kemnitz@mitisft.Convergent.COM (Gregory Kemnitz)
Newsgroups: comp.unix.wizards
Subject: How can a file be truncated on System V??
Summary: I only have a write-only file descriptor
Keywords: link, unlink, directory
Message-ID: <651@mitisft.Convergent.COM>
Date: 28 Apr 89 18:04:47 GMT
Organization: Convergent Technologies, San Jose, CA
Lines: 14


There is an ULTRIX (I think) function

ftruncate(fd, length)
int fd, length;

that takes a file pointed at by fd and truncates the file to length bytes.
The file descriptor may be only open for writing (which rules out dumping
length bytes to a temporary file and copying them back, which involves
read access).  How would one implement such a function in System V (I have
tried the obvious ways, ie fcntl(), etc).  Do you have to write something
to edit the inode to do this??

--Greg