Unix – recursively chmod 755 all directories, and 644 all files
# Current directory
find . -type d -exec chmod 755 {} \;
find . -type f -exec chmod 644 {} \;
# WordPress wp-content folder
find public_html/wp-content -type d -exec chmod 755 {} \; && find public_html/wp-content -type f -exec chmod 644 {} \;