Bash script to test if a given user can read a directory and all files inside?

Question

I need to test in a bash script if a given user can read a given directory with all files and sub-directories inside. The script runs as root.

Assuming the given user name is $user and the directory to test is $dir I added the following line to the script

su -m $user -c "test -r $dir && test -x $dir"
if [ $? -ne ]; then
   echo "$dir is not readable or executable"
fi

Would you suggest correct or improve it?

Answer 1

You could simply say:

su -m $user -c "find $dir >/dev/null 2>&1 || echo $dir is not readable or executable"

This would generate the not readable or executable message if any files/directories within $dir are not readable.

find $dir would return an error code of non-zero if it's not able to read any file.

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EDIT: A more complete (or reliable) way of finding all directories/files that are not readable would be to say:

find . \( -type d -perm /u+r -o -type d -perm /u+x -o -type f -perm /u+r \)