Resize a File, without rewrite it!

gmpassos has asked for the wisdom of the Perl Monks concerning the following question:

How can I resize a file without rewrite it?

To grow the size is easy, just write some data to it. But how to reduce the size?! How can I open a file, that already exist, and just cut some data in the end without need to rewrite all of it?! Just imagine that the file can have 500Mb! I really can't rewrite it just to reduce the size.

Graciliano M. P.
"The creativity is the expression of the liberty".

Comment on Resize a File, without rewrite it!

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Re: Resize a File, without rewrite it! by zengargoyle (Deacon) on Mar 10, 2003 at 20:17 UTC
`truncate(FILE, $newlen);` [download] `perldoc -f truncate` is likely what you want.	[reply] [d/l]
Re: Re: Resize a File, without rewrite it! by gmpassos (Priest) on Mar 10, 2003 at 23:38 UTC
Thanks for the reply! it works. But you need to open your file to append data before: `open (LOG,">>$file") ; truncate(LOG, 3); close (LOG) ;` [download] Graciliano M. P. "The creativity is the expression of the liberty".	[reply] [d/l]
Re: Resize a File, without rewrite it! by Elian (Parson) on Mar 10, 2003 at 20:18 UTC
Truncate takes a parameter, which is the new filesize. This will, on at least some operating systems, shrink the file. (This isn't 100% cross-platform, but should work most places)	[reply]