Hello Bob,
Hello @Lists,
countobjects()
{
myline=0
cat $objectcountfile|grep -v "^[^0-9]*$"|grep -v "^0$"|
awk '{myline += $1} END {print myline}' > $objectsum
}
this gave me the right behavior.
THX
i ve forgotten that the piping opens another subshell,
so it is clearly logical that the 2 variables have the same name,
but are not identical :-)
thanks for all
michael
2006/6/1, Bob Willcox <[EMAIL PROTECTED]>:
On Thu, Jun 01, 2006 at 04:28:39PM +0200, Michael Schuh wrote:
> Hello,
>
> i have a little problem with the
> scope of sheel variables in an script.
> the script shows like:
>
> #!/bin/sh
> objectcountfile=/data2/scout/objects
> objectsum=/data2/scout/objcount
> sometime=5
> initialize()
> {
> [ ! -e $objectsum ] && touch $objectsum
> }
> #
> countobjects()
> {
> myline=0
> cat $objectcountfile|grep -v "^[^0-9]*$"|grep -v "^0$"| while read line
> do
> myline=`expr $myline + $line`
> echo $myline > $objectsum
> done
> }
> initialize
> while true
> do
> countobjects
> clear
> echo bla bla
> cat $objectsum
> sleep $sometime
> done
> ##end script
>
> this script does what i want, but, i dont really want put
> the count ($myline) every time he changes in $objectsum.
> this wasnt really neccessary only the result over all interests me.
> so my first script was
> ##
> countobjects()
> {
> myline=0
> cat $objectcountfile|grep -v "^[^0-9]*$"|grep -v "^0$"| while read line
> do
> myline=`expr $myline + $line`
> done
> echo $myline > $objectsum
> }
> ##
> but this doesnt function right. so i see the behavior from $myline in the
> while-loop like an local variable......
With:
while ...
do
...
done
The statements within the do...done sequence are run in a subshell and
therefore all variables referenced by those statements are local to
that subshell. Consequently, the myline variable that is outside of the
do...done sequence is a *different* variable (and will still be null in
your example).
I'm not sure what your data looks like, but one possible solution would
be to use awk to read the lines and do the addition, perhaps like this:
countobjects()
{
myline=0
cat $objectcountfile|grep -v "^[^0-9]*$"|grep -v "^0$"|
awk '{myline += $1} END {print myline}' > $objectsum
}
Note that I didn't actually run the above code, but I think it's
correct, and if not, it should be pretty close to what you need.
Of course, you could replace the cat and 2 greps with some additional
awk stuff (and improve performance), but I wanted to keep it as simple
and close to your example as possible.
>
> i have searched in man-pages and in google but i have
> not really good points found.
>
> Can anyone give me an ligthshed on this problem?
> Please answer me directly, i be out of freebsd-hackers.
I recommend some good shell & awk programming books.
Hope this helps,
Bob
>
> thanks
>
> michael
> _______________________________________________
> freebsd-stable@freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-stable
> To unsubscribe, send any mail to "[EMAIL PROTECTED]"
--
Bob Willcox Grabel's Law:
[EMAIL PROTECTED] 2 is not equal to 3 -- not even for large values
Austin, TX of 2.
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