How do I SHORTEN a file without rewriting it?

[Michael Henning]

alex at bilver.UUCP (Alex Matulich) writes:

>Is there a way to shorten a file, that is, chop some data off the end of
>it, so that it doesn't consume as much physical space on the disk?  The
>file I have is too big to read into memory and write back out again, and
>there is not enough room on the disk to write out a temporary file.

Ftruncate() (BSD call) will do the job. Under AIX (maybe others), there
is an fclear() call that allows you to punch holes into a file at arbitrary
places. The blocks corresponding the hole(s) are returned to the file system.
In SysV.4, you can use fntl() to do the same.

							Michi.

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