On 01-Jun-07 10:04:52, Dan Hatton wrote:
Dear All,
When standard output is redirected to a file, it gets cached, so that nothing is actually written to the file until (say) 4kB of standard output has built up. I'm sometimes too impatient to wait that long to see the output of my programs, especially when the program in question is a long, slow numerical calculation that might be producing only a few hundred bytes of output per day. Is there any way of either switching off this caching, or inspecting the contents of the cache before it gets written, please?
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Thanks very much
Dan Hatton
I just realised that I inadvertently, in my previous response, answered your "Is there any way of ... inspecting the contents of the cache before it gets written?" in the affirmative!
Namely, as I put in as an afterthought, use "tail -f". Example:
Have 2 xterms going. In xterm 1:
echo `date` > myoutfile
(note backquotes). In xterm 2:
tail -f myoutfile
and see one line like "Fri Jun 1 12:38:45 BST 2007". Now, in xterm 1:
while true ; do echo `date` >> myoutfile ; sleep 2 ; done
and watch the output accumulate in xterm 2, every 2 seconds (i.e. you're seeing it before the cache gets flushed). So far:
Fri Jun 1 12:38:45 BST 2007 Fri Jun 1 12:40:31 BST 2007 Fri Jun 1 12:40:33 BST 2007 Fri Jun 1 12:40:35 BST 2007 Fri Jun 1 12:40:37 BST 2007 Fri Jun 1 12:40:39 BST 2007 Fri Jun 1 12:40:41 BST 2007 Fri Jun 1 12:40:43 BST 2007 Fri Jun 1 12:40:45 BST 2007 Fri Jun 1 12:40:47 BST 2007 Fri Jun 1 12:40:49 BST 2007 Fri Jun 1 12:40:51 BST 2007 Fri Jun 1 12:40:53 BST 2007 Fri Jun 1 12:40:55 BST 2007 Fri Jun 1 12:40:57 BST 2007 Fri Jun 1 12:41:00 BST 2007 Fri Jun 1 12:41:02 BST 2007 Fri Jun 1 12:41:04 BST 2007 Fri Jun 1 12:41:06 BST 2007 Fri Jun 1 12:41:08 BST 2007 Fri Jun 1 12:41:10 BST 2007 Fri Jun 1 12:41:12 BST 2007
Kill either program with ^C when desired.
Ted.
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