There is a din mentioned in Maseches Sofrim (14:15) and brought down l’halachah (91:63) that it is forbidden to mention the name of Hashem without a head covering. The question is, if one has a friend called Sholam (which is one off Hashem’s name) is he allowed to call his name if he is not wearing a head covering. The Shulchan Aruch (84) rules that to wish people sholam in a bathhouse in a place where everyone is undressed is forbidden. The Mishnah Berurah explains, that the reason one should refrain from doing so is because, Sholam is one of the names of Hashem. However, when it comes to calling a person who is called Sholam by his name in the bathhouse the Mishnah Berurah cites a machlokes haposkim, if doing so is allowed. The Mishnah Berurah concludes by citing the Tevuas Shor, that one may be lenient, however, one who has yiras Shomayim should try and be stringent as many Achronim forbid doing so, and one should swallow the ‘mem’ of Sholam and should just say “Shalo”. Based on the above, presumably the same thing should be in regards to our shailah, and if one has no head covering he should avoid calling his friend Sholam and he should call him Shola or try and avoid mentioning the name altogether.
If one is wearing a head covering, however, his friend isn’t, one should refrain from greeting his friend with “sholam aleichem” as he will cause his friend to respond with “sholam aleichem”, and he will end up saying “sholam” without a head covering. The above is also very practical when one is sitting in the barbers having a haircut. One should refrain from wishing him “sholam” as this will cause him to answer back, without a hear covering. R’ Moshe (Igros Moshe, Orach Chaim 4:40:24) rules like the above. However, he adds, if one is worried that his friend will be angry etc. then one doesn’t need to be stringent, however, he should start the conversation by saying “what’s news with you etc.” and should try and avoid saying “sholam” (see also Sdei Chemed, Vol. 1, Mareches 1:13 d.h. u’linyan).
