Look at these 2 similar scripts:
(1)
echo -e "aaa\nbbb\nccc\nddd" >tmp
value=0;
while read line; do
value=`expr $value + 1`
echo $value
done <tmp
rm -f tmp
echo "at last: $value"

result:
1
2
3
4
at last: 4

(2)
value=0
echo -e "aaa\nbbb\nccc\nddd" | while read line; do
value=`expr $value + 1`
echo $value
done
echo "at last: $value"

result:
1
2
3
4
at last: 0

I don't want to add a 'tmp' file, is there any other way? And I also
want to know what makes the differences.

Thank you

Roc Zhou <chowroc.z@gmail.com> wrote:
> Look at these 2 similar scripts:
> (1)
> echo -e "aaa\nbbb\nccc\nddd" >tmp
> value=0;
> while read line; do
> value=`expr $value + 1`
> echo $value
> done <tmp
> rm -f tmp
> echo "at last: $value"
>
> result:
> 1
> 2
> 3
> 4
> at last: 4
>
> (2)
> value=0
> echo -e "aaa\nbbb\nccc\nddd" | while read line; do
> value=`expr $value + 1`
> echo $value
> done
> echo "at last: $value"
>
> result:
> 1
> 2
> 3
> 4
> at last: 0
>
> I don't want to add a 'tmp' file, is there any other way? And I also
> want to know what makes the differences.

Try this script and see if it gives you any clues:

echo "---" >tmp
while read line; do
ps aux | grep "$0" | grep -v grep
done <tmp
rm -f tmp

echo "---"
echo line | while read line; do
ps aux | grep "$0" | grep -v grep
done

--
Kenan Kalajdzic

On 2007-05-16, Roc Zhou wrote:
> Look at these 2 similar scripts:
> (1)
> echo -e "aaa\nbbb\nccc\nddd" >tmp
> value=0;
> while read line; do
> value=`expr $value + 1`
> echo $value
> done <tmp
> rm -f tmp
> echo "at last: $value"
>
> result:
> 1
> 2
> 3
> 4
> at last: 4
>
> (2)
> value=0
> echo -e "aaa\nbbb\nccc\nddd" | while read line; do
> value=`expr $value + 1`
> echo $value
> done
> echo "at last: $value"
>
> result:
> 1
> 2
> 3
> 4
> at last: 0
>
> I don't want to add a 'tmp' file, is there any other way? And I also
> want to know what makes the differences.

See the FAQ: <http://cfaj.freeshell.org/shell/cus-faq.html#JJ>

--
Chris F.A. Johnson, author <http://cfaj.freeshell.org/shell/>
Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
===== My code in this post, if any, assumes the POSIX locale
===== and is released under the GNU General Public Licence

I got it, Thank you very much.

On 5ÔÂ17ÈÕ, ÉÏÎç12ʱ08·Ö, "Chris F.A. Johnson" <cfajohn...@gmail.com> wrote:
> On 2007-05-16, Roc Zhou wrote:
>
>
>
> > Look at these 2 similar scripts:
> > (1)
> > echo -e "aaa\nbbb\nccc\nddd" >tmp
> > value=0;
> > while read line; do
> > value=`expr $value + 1`
> > echo $value
> > done <tmp
> > rm -f tmp
> > echo "at last: $value"
>
> > result:
> > 1
> > 2
> > 3
> > 4
> > at last: 4
>
> > (2)
> > value=0
> > echo -e "aaa\nbbb\nccc\nddd" | while read line; do
> > value=`expr $value + 1`
> > echo $value
> > done
> > echo "at last: $value"
>
> > result:
> > 1
> > 2
> > 3
> > 4
> > at last: 0
>
> > I don't want to add a 'tmp' file, is there any other way? And I also
> > want to know what makes the differences.
>
> See the FAQ: <http://cfaj.freeshell.org/shell/cus-faq.html#JJ>
>
> --
> Chris F.A. Johnson, author <http://cfaj.freeshell.org/shell/>
> Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
> ===== My code in this post, if any, assumes the POSIX locale
> ===== and is released under the GNU General Public Licence