Shell Programming and Scripting

#!/bin/bash

SIZE=`ls -s text.txt`

while [ "$SIZE" != '0 text.txt' ]
do
[ my intructions ]
done

while test -s somefile.txt; do
  file is not empty...
done

# number of chars in file
size=$(cat file | wc -c)
while ((size>0))
do
      do_something
      # look again
      size=$(cat file | wc -c)
done

while [ -s file ]
do
      do_something
done

 
echo "Hi" > test_file
while [ -s test_file ]
do
echo "In while loop"
echo "Doing something - assuming that you will make test_file blank withing the loop itself"
echo "Creating test_file of 0 bytes so that this loop can be stopped."
rm test_file
touch test_file
done

while true
do
        if [ -s test.txt ]
        then
                echo "my instructions"
                break
        else
                # Wait a reasonable time before trying again
                sleep 5
        fi
done