Date: Fri, 7 Jul 2006 20:23:50 +0100 (BST) From: Jan Grant <jan.grant@bristol.ac.uk> To: freebsd-standards@freebsd.org Subject: stdio/sh behaviour guaranteed? Message-ID: <20060707201402.T14116@tribble.ilrt.bris.ac.uk>
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Consider the following snippet.
[[[
#!/bin/sh
echo one > t
while read line
do
echo $line
case $line in
one) echo two >> t
;;
two) echo three >> t
;;
esac
done <t
]]]
This produces three lines of output on FreeBSD: which is what I'd
intuitively expect and it's certainly useful behaviour.
I'm just trying to determine if that behaviour is one that I can rely on
- in other words, I guess, if stdio performs a "short read" that fails
to fill a buffer, and the underlying file is then extended outside the
process, will another attempt to read from the FILE* (or a test of feof,
say) honour the new, longer file contents? And in particular, is the
idiom above blessed by appropriate posix standards?
I'm having a hard time pinning down any appropriate standards that deal
with this.
Cheers,
jan
PS. Would appreciate a CC: on any responses.
--
jan grant, ISYS, University of Bristol. http://www.bris.ac.uk/
Tel +44 (0)117 3317661 http://ioctl.org/jan/
Not as randy or clumsom as a blaster.
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