Switch user ID (UNIX)
You must specify the options and arguments in this order:
su [-] [username] [-c command]
The su utility lets you temporarily become another user, then return to your regular user ID.
The su utility requests the password of the given username and changes to that username, invoking its shell but modifying only essential elements of the environment. Only the HOME, PATH, and possibly SHELL environment variables are changed, but the new shell has the rights and privileges of the user specified. The new username remains in effect until this shell exits.
|This utility needs to have the setuid (“set user ID”) bit set in its permissions. If you use mkefs, mketfs, mkifs, or mkqnx6fs on a Windows host to include this utility in an image, use the perms attribute to specify its permissions explicitly, and the uid and gid attributes to set the ownership correctly.|
Logging In, Logging Out, and Shutting Down in the Neutrino User's Guide