🚀 go-pugleaf

In article <1162@bilver.UUCP> alex@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?

It is a poorly documented but reliable feature of MS-DOS systems that a
zero length write truncates a file.  That is, you seek to where you want
the EOF to be, then do a write(fd, "", 0) or the equivalent.

Note that if you're using a stdio library (fopen et al.) you almost certainly
cannot do this with fwrite.  Also, if your stdio is doing lf to cr/lf
translation, you may need to turn that off as well.

Also note that this hack is extremely unportable.  Unix systems, for
example, have a variety of ways of truncating files (ftruncate, fcntl, etc.)
none of which involve a zero-length write.

Regards,
John Levine, johnl@esegue.segue.boston.ma.us, {spdcc|ima|world}!esegue!johnl
-- 
John R. Levine, IECC, POB 349, Cambridge MA 02238, +1 617 864 9650
johnl@esegue.segue.boston.ma.us, {ima|spdcc|world}!esegue!johnl
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