我是bash脚本的新手，我正在尝试制作一个将一个大文件拆分为多个文件的脚本。我成功地使用了case语句，但没有case语句我怎么做呢？例如，如果我有一个有30百万行的文件（某个数据库文件）。提前感谢！

echo File which one you want to split
read pathOfFile
echo
countLines=`wc -l < $pathOfFile`
echo The file has $countLines lines
echo
echo In how many files do you want to split?
echo -e "a = 2 files\nb = 3 files\nc = 4 files\nd = 5 files\ne = 10 files\nf = 25 files"
read numberOfFiles
echo
echo The files name with should start:
read nameForFiles
echo

#Split the file
case $numberOfFiles in
a) split -l $(($countLines / 2)) $pathOfFile $nameForFiles;;
b) split -l $(($countLines / 3)) $pathOfFile $nameForFiles;;
c) split -l $(($countLines / 4)) $pathOfFile $nameForFiles;;
d) split -l $(($countLines / 5)) $pathOfFile $nameForFiles;;
e) split -l $(($countLines / 10)) $pathOfFile $nameForFiles;;
f) split -l $(($countLines / 25)) $pathOfFile $nameForFiles;;
*) echo Invalid choice.
esac