Changing permissions can be tricky, because either way, permissions are on of the corner stones of security. It could be that you want to change permissions recursively on all folders, but not on files, and vice versa. Unfortunately, a lot of people don’t take that into account.
So here’s a quick tip on how to achieve this.
To recursively give directories specific privileges:
find /path/to/base/dir -type d -exec chmod 755 {} +
To recursively give files specific privileges:
find /path/to/base/dir -type f -exec chmod 644 {} +
Or, if there are many objects to process:
chmod 755 $(find /path/to/base/dir -type d) chmod 644 $(find /path/to/base/dir -type f)
Or, to reduce chmod spawning:
find /path/to/base/dir -type d -print0 | xargs -0 chmod 755 find /path/to/base/dir -type f -print0 | xargs -0 chmod 644