====== Selective chmod for directories and files ======
Here’s how to apply one set of permissions to all files, and a different set of permissions to all directories, in Linux (example):

First cd to the directory containing the subdirectories and files you want to change.  Then:

For directories:

<code bash>find . -type d -exec chmod 755 {} \;</code>

For files:

<code bash>find . -type f -exec chmod 644 {} \;</code>

(You’ll need to change the 755 and 644 to the actual permissions you want, obviously.)