one two
three
fish hat
cat hop

one two three
fish hat cat hop

#!/bin/bash
#

# input and output files
FILE=$1
FILE2=$2

#checks to see if the input file exists
if  [ -f $FILE ];then
echo "file $FILE  found!"
else
echo "file $FILE does not exist"
exit 1
fi

#check to see if output file is empty
 if [ -s $FILE2 ]; then
echo "$FILE2 already has data!"
exit 1
fi

#Joins every two input lines
while read first; do read second; echo "$firstLine $secondLine";
done < $FILE

 cat $FILE &> $FILE2

cat $file | paste -d ' ' - -

cat $file | paste -d ' ' - - > $file2

done < $FILE

 cat $FILE &> $FILE2

done <$FILE >$FILE2