# Recursively set All users with permissions to read files and execute directories.
# If the object is a directory the Executable Bit is added for all users: dr-xr-xr-x.
# If a file has an executable bit, execute is granted for All users: -r-xr-xr-x.
# If the file did not have an executable bit set, no executable bits are modified: -r--r--r--.
chmod -R a=rX testdir/