On 26/02/2016 14:04, Matthijs Nescio wrote:
Hi,
I have the strangest problem. I am running some complicated advanced Bourne
shell scripting. These scripts work fine under Ubuntu 14.04 LTS. However, in
Cygwin I have to add some strange commands with no obvious effect; without
these the scripts just hang. I can not disclose the scripts completely because
they are company property. I realise that this does not comply to the rules of
smart questions, but if anybody else has this problem the Cygwinners need to
know about it. I do not exactly know when these problems started. I reinstalled
Cygwin twice, several weeks ago and yesterday evening.
I have had this problem with several complicated, lengthy scripts. Debugging
using echo debug statements is hard because the echo makes the problem go away.
When I discovered similar problems in multiple scripts, I reinstalled Cygwin,
but the problem persists. Also rebooting my Windows 7 Enterprise edition
machine does not solve the problem. I have had some experienced colleagues to
look at this and they were as flabbergasted as I was.
Examples:
TTP_FILE_DR_KML=`echo $TTP_FILE.dr.kml | sed -s 's#\.txt\.#\.#g'`
#echo -n> /dev/null
sleep 0
if [ "`convert_needed "$TTP_FILE_DR_KML"`" = "convert" ]
then
In the examples above and below, either the sleep or the echo has to be
commented in, otherwise the script just hangs. In the example below the doit
function needs the echo or sleep, otherwise it does not return.
doit()
{
# 8< code removed
#echo -n
sleep 0
}
In
order to investigate this problem the Cywinners will need more information.
Feel free to ask, but it may not be legal for me to share.
Questions:
* Was a similar issue ever reported? I have looked, but did not find anything.
* Is there a solution?
Thank you, kind regards, Matthijs.
I suspect you hit a corner case of resource race.
May be as the time for execution is very short :
$ time echo -n > /dev/null 0
real 0m0.000s
user 0m0.000s
sys 0m0.000s
$ time sleep 0
real 0m0.070s
user 0m0.015s
sys 0m0.062s
As both the two commands are just supposed to waste minimal time,
what was the original need of both of them ?
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