while read 2 times on shell script don’t work - sh

Question

I'm working on a script and when I try to use the while read 2 times the first loop only work once.
un=$(echo $LOGNAME | tr '[A-Z]' '[a-z]')
grep -v '^#' nodeteste.txt > auxiliar.txt
while read line
do
ssh "$un#$line" "cat arquivo" > arquivo.externo
cut -d "," -f 1 arquivo.externo > arquivo.externo.cut
uniq arquivo.externo.cut > arquivo.externo.cut.uniq
while read line2
do
valor=$(grep -c "$line2 " arquivo.base)
if [ $valor -eq 0 ]; then
echo $line >> arquivo.base.diferente
echo $line2 >> arquivo.base.diferente
grep -i "$line2," arquivo.externo >> arquivo.base.diferente
echo $line $line2 $valor "eh diferente"
fi
done < arquivo.externo.cut.uniq
done < auxiliar.txt
rm auxiliar.txt
I'm think I lose the stdin/out anytime but I’m stuck here, any ideas?

Answer 1

To see what is happening, in the loops, strip the script from all the unnecessary stuff:
while read line ; do
echo "outer: $line"
while read line2 ; do
echo "inner $line2"
done
done
When you run this, you'll get
test
outer: test
test
inner test
test
inner test
^Dtest
outer: test
test
inner test
^D^D
When you take the input from a file, it becomes different. For example: create a file a:
a
a
a
a
a
and a file b:
b
b
b
b
b
and do:
while read line ; do
echo "outer: $line"
while read line2 ; do
echo "inner $line2"
done <b
done <a
The result will be:
outer: a
inner b
inner b
inner b
inner b
inner b
and not 5x the outer circle.
A solution would be:
for line in $(<a) ; do
echo "outer: $line"
for line2 in $(<b) ; do
echo "inner $line2"
done
done
outer: a
inner b
inner b
inner b
outer: a
inner b
inner b
inner b
outer: a
inner b
inner b
inner b
(I've made the a and b a bit shorter)

Answer 2

Here i found the problem, the ssh uses de stdin causing the 1 loop to only work once, when i use -n option the sdtin is redirect.
Problem source:
ssh "$un#$line" "cat arquivo" > arquivo.externo
Works source:
ssh -n "$un#$line" "cat arquivo" > arquivo.externo
SSH Manual:
-n Redirects stdin from /dev/null (prevents reading stdin).