Temporarily, I have to use a cane in order to get to shul on Shabbat. There is no eruv in our neighborhood, I wonder whether carrying a cane, essential for walking, is permitted or forbidden?
A cane is only permissible for someone who is totally immobile without it. One who can walk even a short distance without a cane may not use it where there is no eruv [even though for the long distance the cane is necessary].
Shulchan Aruch O:C 301:17, see Biur Halacha ibid. who brings 2 opinions whether this is a Biblical prohibition of carrying or a Rabbinic decree due to concern that one may walk 4 amos without resting on the cane.