By pressing r you can read something.
- fortune cookies, to read the fortune without eating the cookie.
- T-shirts, and in 3.6.0, aprons, to examine the message on each item.
- scrolls, to activate them.
- spellbooks, to study them.
You can try unsuccessfully to read other classes of objects.
In vanilla NetHack, you automatically read any floor engravings or headstones that you encounter. This does not use the r command, nor does it break illiterate conduct. (Though the read command does not break the conduct, the engrave command does.)
In NetHack brass, you automatically read any floor engravings, but not headstones. To read headstones, press r and then answer y to the question, "Do you want to read an epitaph on the grave?" In brass 040923, reading the epitaph does not break illiterate conduct.
By pressing r then ,, you can read objects that are on the floor. Thus, if you suddenly need to flee and you have no empty inventory slots, but luckily found a scroll of teleportation on the floor, SLASH'EM lets you activate it.
SLASH'EM lets you "read" rings. This is a feature to check the color of rings that you are currently wearing, otherwise "You can't see it!" or "Perhaps you should put it on first." Currently, only a mood ring will glow with color; any other ring gives the message, "There seems to be nothing special about this ring."