The Sages teach that the word "Shalom" – which is commonly used as a friendly greeting – is also one of the Names of the Almighty. The question thus arises, is it permissible to extend such a greeting while one's head is uncovered? For example, if while taking a haircut one sees his friend enter the barbershop, may he extend a greeting of "Shalom Aleichem," or would this be forbidden? Or, if somebody meets a friend who, for whatever reason, is not wearing a Kippa, may he greet him with "Shalom Aleichem" knowing that the friend will likely respond by saying, "Aleichem Shalom"?

Hacham Ovadia Yosef, in his work Yabia Omer, rules that one may, in fact, extend a greeting of "Shalom" with his head uncovered. For one thing, he notes, in such a case the individual obviously does not use the word "Shalom" in reference to God. Furthermore, some authorities maintain that this divine Name has a lower Halachic status than the other Names of God, and thus may be recited even while one's head is not covered. Nevertheless, Hacham Ovadia emphasizes, this leniency does not apply to places deemed "impure," such as a bathhouse or a Mikveh. In these places, Halacha forbids greeting a friend with the word "Shalom," insofar as this word is also one of the Names of the Almighty.

Summary: One may greet somebody with the word "Shalom" while his or the friend's head is uncovered, such as while taking a haircut. However, one may not extend this greeting in a bathhouse or Mikveh.