While Loop Logic

Shell Programming and Scripting
1

I would need to with making while loop logic working in shell program when I am new into the shell programing
1) I would need to try to get the file from the remote side ----need to try 15 mins apart for 4 times and terminate the program if file is not available....

I would need to know how I can setup counters to try in while loop ......

as I have sample at below. Please assist

==============================================
for file in $FILES; do
echo
echo "About to Retrieve $file from $SOU$SRDIR"
echo "via $proxy"
echo
err=1
while [ "$err" != 0 ]; do
ssh -x $proxy ftp "$SOU$SRDIR$file"
err=$?
if [ "$err" != 0 ]; then
echo "File transfer failed. Bummer. $err"
echo "Trying again in 15 minutes"
sleep 900
fi
done
echo " Retrieving file $file ..."
scp -p $proxy:~/$file .
chmod 666 $file
ls -l $file
ssh -x $proxy rm $file
done

2

syntex of while loop:
x=0;
while( $x -lt 10);do

steps;
x=x+1
done

3

for file in $FILES
do
echo "About to Retrieve $file from $SOU$SRDIR"
echo "via $proxy"
err=1
cnt =1
while [ $cnt -le 4 ]
do
ssh -x $proxy ftp "$SOU$SRDIR$file"
err=$?
if [ "$err" != 0 ]
then
echo "File transfer failed. Bummer. $err"
echo "Trying again in 15 minutes"
sleep 900
cnt=`expr $cnt + 1`
else
break;
fi
done

echo " Retrieving file $file ..."
scp -p $proxy:~/$file .
chmod 666 $file
ls -l $file
ssh -x $proxy rm $file

done

4

Or simply just

for attempts in one two three four;
  REMAINING=
  for file in $FILES; do
    echo
    echo "About to Retrieve $file from $SOU$SRDIR"
    echo "via $proxy"
    echo
    if ssh -x $proxy ftp "$SOU$SRDIR$file"; then
      echo " Retrieving file $file ..."
      scp -p $proxy:~/$file .
      chmod 666 $file
      ls -l $file
      ssh -x $proxy rm $file
    else
      echo "File transfer failed. Bummer. $err"
      echo "Trying again in 15 minutes"
      REMAINING="$REMAINING $file"
    fi
  done
  case $REMAINING in '') break;; esac
  FILES=$REMAINING
  sleep 900
done
5

It works! You guys are very helpful.