Pants, t-shirts, and long-sleeve shirts are acceptable as clothes to wear in Egypt. Avoid wearing shorts or sleeveless shirts to fit in with local customs. Men do not need a head-covering scarf to enter mosques.
Do you have to cover your skin in Egypt?
As a tourist you aren't expected to wear a hijab or any other hair or facial covering in Egypt. What is this? The only exception to this is if you're visiting a mosque – in that case, you do indeed need to respect the fact that you're entering a religious building and cover up.