Ensel Sharon wrote:
I have a script that, among other things, removes a line from
/etc/ftpchroot.
I do this with this method:
cat /etc/ftpchroot | grep -v $remove > /etc/ftpchroot
Easy. You cat all of the file except the line you want to remove, and
redirect it back to itself.
The problem is, about 50% of the time, I end up with an empty ftpchroot
file. It is zero bytes. This obviously has nothing to do with a bad
variable, since if it wasn't there, the starting file and ending file
would just be identical.
Instead, I get an empty file. I have reproduced this with other files in
other places - works some of the time, other times gives me an empty file.
What gives ?
(note, I know a lot of ways to work around this - so I'm not so much
asking how to fix this, as I am asking "why does this happen" ?)
I can't answer your question except to say that I have always redirected
to a tmp file, and then replaced the original after safely closing it
and testing the tmp file for whatever results I expect.
Just dumping output to overwrite the file I am currently reading was
always bad juju in my book.
DAve
--
Three years now I've asked Google why they don't have a
logo change for Memorial Day. Why do they choose to do logos
for other non-international holidays, but nothing for
Veterans?
Maybe they forgot who made that choice possible.
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