Shell编程（错在哪）

#!/bin/bash
dir=${1-`pwd`}
echo "Big file(in blocks) under dirtectory \"$dir\"."
for i in `find -size +2048 -print`
do
if[ -f "${i}" ]
then
ls -s "${i}"
fi
done
exit 0
提示：
Big file(in blocks) under dirtectory "/home/xxxxx".
./bigfile: line 7: 在未预料的“then”附近出现语法错误
./bigfile: line 7: ` then'