Date: Mon, 30 Oct 2006 10:30:57 -0500 (EST) From: Ensel Sharon <user@dhp.com> To: freebsd-questions@freebsd.org Subject: file redirect is destroying the file ? Help! Message-ID: <Pine.LNX.4.21.0610301027260.2785-100000@shell.dhp.com>
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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" ?)
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