Question

I have never done shell scripting before and need some help with a small project.

I want a user to enter three file names and check that the user has input THREE names and give an error if its more or less. The files will be sorted into another file but that is working fine just having problem with checking what the user has entered.

I have tried

echo Please select the three files you want to use
read $file1 $file2 $file3

if ! [ $# -eq 3 ]; then
   echo "Please enter THREE values"
fi 

Answer 1

Without changing your read command:

if [ -z "$file1" -o -z "$file2" -o -z "$file3" ]; then
    echo "Please enter THREE values"
fi

But the preferred way is using arrays here:

read -a files
if [ ! ${#files[@]} -eq 3 ]; then
    echo "Please enter THREE values"
fi

And btw. the elements are ${files[0]}, ${files[1]} and ${files[2]} or, you could loop the array:

for f in "${files[@]}"; do
    echo $f
done